Doutorado em Ciências Fisiológicas

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Análise da precisão e da aplicabilidade do consumo de oxigênio de reserva durante o exercício aeróbio contínuo nas intensidades de 50% a 80% do consumo máximo de oxigênio
(Universidade Federal do Espírito Santo, 2007-03-27) Santos, Miguel Angelo Alves dos; Orientador1; https://orcid.org/; http://lattes.cnpq.br/; 1º membro da banca
The main objective of this study was to evaluate the accuracy and the applicability of oxygen consumption reserve (VO2R) in the prescription of continuous aerobic exercise for the maximal oxygen consumption (VO2max) intensities of 50%, 60%, 70%, and 80%. Following ergoespirometry, the physical training speeds corresponding to 50%, 60%, 70%, and 80% VO2R were calculated using the equation proposed by ACSM for running and walking in 60 volunteers – 30 males and 30 females – aged 23 ± 3.4 and 21.7 ± 4.1 respectively. After the calculations were done, the volunteers performed continuous aerobic exercise (running or walking) for 30 minutes in a random sequence of the said intensities with intervals of 48 hours between them. During the exercise performance, oxygen consumption was collected. The VO2 consumption collected during the aerobic exercise was called measured oxygen consumption reserve (VO2Rm) for the purpose of comparing VO2R calculations with VO2 consumption at the same exercise intensity. The criteria used for determining the equation accuracy were the following: a) Student’s t test; b) evaluation of the correlation coefficient; c) analysis of estimate standard error of the inclination of the straight line of linear regression. The level of significance used was p< 0.05. Data demonstrated that VO2R and VO2Rm were similar in all intensities. However, the VO2R median values were always higher at each intensity studied than those of VO2Rm (3.4%, 4.2%, 9.2%, and 2.2% in the male group and 9.9%, 3.3%, 7.7%, and 9.7 % in the female group). There was no significant difference between the heart rate measured in the blood lactate (BL) and the heart rate at 70% of HRmaxE and 70% of HRmaxM. The heart rate values prescribed indirectly 85% of HRmaxE and 85% of HRmaxM underestimate the heart rate in the RCP by approximately 6.5% (male group) and 9.1% (female group). The VO2 values prescribed indirectly overestimate by approximately 36.7% (male group) and 66.3% (female group) when VO2 at 60% of the estimated oxygen maximal consumption (VO2maxE) is used and by 18% when VO2 at 60% of VO2maxM is used compared to VO2 values in BL, both groups. There was no significant difference between VO2 in RCP and VO2 at 80% of VO2maxM; however, VO2 in RCP was approximately 9.2% higher in the male group and 6.5% lower in the female group. We came to the conclusion that the oxygen consumption reserve equation demonstrates a good correlation with the VO2 consumed during continuous aerobic exercise; however, the said equation tends to overestimate the aerobic exercise intensity mainly in individuals with poor physical condition. Moreover, the use of both VO2maxE and HRmaxE overestimates the values found, which may predispose to a premature metabolic acidosis, and, as a result of that, cause an overload to the cardio-vascular system. The results suggest that adequate prescriptions of intensities for aerobic exercising are more efficient and safer when determined by ergoespirometry.
Avaliação do Tratamento a Curto Prazo Com Ouabaína na Reatividade Vascular de Rato.
(Universidade Federal do Espírito Santo, 2007-04-04) Padilha, Alessandra Simão; Stefanon, Ivanita; Vassallo, Dalton Valentim; Mill, José Geraldo; Rossoni, Luciana Venturini; Moreira, Cleci Menezes
Ouabain (OUA), an inhibitor of the Na+K+ ATPase (NKA), is an endogenous compound present in namolar concentration in the plasma of several mammalians. In several models of hypertension plasma OUA concentration is increased suggesting an association to the genesis and/or maintenance of hypertension. In this study pressor changes resulting from the acute administration of OUA 18µg/Kg (i.v.) (~30 nmol/Kg) were evaluated in normotensive (Wistar and WKY) and spontaneously hypertensive rats (SHR). At the same time, were evaluated the effects of 1µM OUA in the reactivity of the tail vascular bed to phenylephrine (PHE) in Wistar, WKY and SHR. On the order hand, the vascular reactivity and the role of endothelial factors in mesenteric resistance arteries (MRA) in 15 day chronic oubain treated rats were also investigated. The systolic (SBP) and diastolic (DBP) blood pressure were increased by the acute administration of 18µg/Kg of OUA in Wistar and SHR, but not in WKY. The pretreatment with losartan (10 mg/kg), an inhibitor of AT1 receptors, only blocked the effects of OUA in the DBP in Wistar, without altering the other parameters. In the tail vascular bed, the perfusion with OUA in the presence of endothelium (E+) increased the vascular reactivity of PHE in the all groups. In the absence of functional endothelium, the effects of OUA were abolished. However, in E+, after perfusion with losartan (10-4M) plus OUA, the increase of response to PHE by OUA was totally abolished in Wistar and WKY, and partially in SHR. The chronic ouabain treatment for 15 days increased SBP, DBP and heart rate. However, this treatment did not change the pressor response to PHE. The endothelium removal or the nitric oxide synthase (NOS) inhibitor (L-NAME, 10-5M) increased the responses to α-adrenergic agonists. The endothelial modulation was similar in treated and untreated rats, but the L-NAME effects were more increased in MRA in treated rats. Endothelial NOS expression and relaxation of acetilcholine remained unaltered after ouabain treatment. To evaluated the prostanoids participation in the response to PHE, the MRA were incubated with Indometacin (10-4M), an inhibitor of cyclooxigenase, plus LLNAME. In the same protocol, EDHF participation was investigated, after incubation of MRA with Indometacin and L-NAME plus TEA (2mM), an inhibitor of calcium activated potassium channels. Indometacin plus L-NAME, shifted leftward the concentration-response curves to PHE in MRA from untreated rats and this response was similar when compared the leftward shift after incubation only L-NAME. However, in MRA of the treated rats, the co-incubation with Indometacin plus L-NAME did not altered concentrationresponse curves to PHE. This result was accompanied by increase in the COX-2 expression. TEA shifted the PHE curves further leftward only in MRA from untreated rats. In conclusion, these results suggest that the increase in the DBP in Wistar after 18µg/Kg OUA depends of angiotensin II. In the tail vascular bed of normotensive and hypertensive rats, the acute administration of 1µM OUA, increased of PHE pressor response. The endothelium modulates this response by releasing angiontensin II in normotensive rats, but in hypertensive rats, other factors seem to be involved besides the angiotensina II. The chronic ouabain treatment for 15 days modified the participation of endothelial factors in response to PHE in MRA, by the increase liberation of NO and prostanoids, and impairment of EDHF release. This was accompanied by an increased COX-2 expression. Although this balance avoids changes in the PHE concentration-response curves these vascular changes might contribute to maintain the ouabain-induced hypertension.
Estudo comparativo dos comportamentos exploratórios, predatórios e agonísticos de ratos wistar, selvagens (Rattus norvegicus sp) e linhagens derivadas
(Universidade Federal do Espírito Santo, 2007-05-31) Póvoa, Raner Miguel Ferreira; Schenberg, Luiz Carlos; Palacios, Ester Miyuki Nakamura; Futuro Neto, Henrique de Azevedo; Garcia, Agnaldo; Lucion, Aldo Bolten
abstract
Diferenças no Desempenho das Funções Frontais nos Subtipos de Alcoolismo, de Acordo Com a Tipologia de Lesch
(Universidade Federal do Espírito Santo, 2008-03-27) Zago-Gomes, Maria da Penha; Palácios, Ester Miyuki Nakamura; Xavier, Gilberto Fernando; Marques, Ana Cecília Petta Roselli; Oliveira, Roney Welinton Dias de; Pereira, Fausto Edmundo Lima
Introduction: Alcohol dependence is a heterogeneous disease with a clear variability in clinical presentations, therapeutic results and relapses, indicating different biological vulnerability. Lesch et al (1988) distinguished four categories of alcohol dependence: Type I: with severe symptoms of abstinence; Type II: uses alcohol as a solution for conflicts; Type III: uses alcohol as self-medication for psychiatric symptoms, and Type IV: with a history of neurological lesions preceding the development of alcohol dependence. Cognitive deficits have been usually reported in alcoholics (mainly frontal dysfunction) with direct implications in the treatment. Objectives: This study aimed to evaluate frontal functions in different categories of alcohol dependence according to Lesch’s Typology. Methods: Frontal Assessment Battery (FAB) and Mini-Mental State Examination (MMSE) were applied in 170 alcoholics patients classified into categories according to Lesch’s Typology and in 40 nonalcoholics controls matched for age, gender, socio-demographic characteristics and education. The quotient of intelligence (IQ) was also evaluated in alcoholics. Results: The alcoholics in the present study were classified according to Lesch’s Typology in: Type I = 21.2%, Type II = 29.4%, Type III = 28.8%, and Type IV = 20.6%. It was observed a significant impairment in the performance of tasks demanding cognitive frontal function in patients classified as Type IV as compared to non-alcoholics controls and alcoholics classified as Type I, II and III. This frontal dysfunction was not correlated with the pattern of alcohol intake or with the age for the first use of alcohol, and neither with the education level of the patients. Alcoholics classified as Type IV also showed lower IQ and MMSE scores, and it was the subgroup that showed higher percentage of scores suggesting dementia. However, the frontal dysfunction in this subgroup of alcoholics (Lesch’ Type IV) was still observed even excluding those with dementia scored by MMSE. And yet, this frontal dysfunction was seen even with abstinence over 90 days. In further analysis it was found that the types of alcohol dependence, along with mental and intellectual performance, are factors that can predict a frontal dysfunction. Conclusion: Categorization of clinical type of alcohol dependence by applying a simple classification as Lesch’s Typology, along with mental state and frontal function examinations through the applications of MMSE and FAB instruments, respectively, may be of an extraordinarily relevance in the clinical examination of alcoholics, allowing even the identification of those who have subclinical executive dysfunction, providing significant changes in strategies for individualized approaches, which may be of a great importance in the treatment of alcohol dependence.
Variação Circadiana do Infarto Agudo do Miocárdio em Pacientes Com Apnéia Obstrutiva do Sono.
(Universidade Federal do Espírito Santo, 2008-05-30) Kuniyoshi, Fatima Helena Sert; Vasquez, Elisardo Correal; Meyrelles , Silvana dos Santos; Futuro Neto, Henrique de Azevedo; Negrão , Carlos Eduardo; Fontes , Marco Antonio Peliky
abstract
Modulação dopaminérgica da memória operacional espacial no córtex pré-frontal medial em ratos: envolvimento de receptores dos tipos D1 e D4
(Universidade Federal do Espírito Santo, 2008-06-27) Valentim Junior, Saavedra José Rios; Palacios, Ester Miyuki Nakamura; Mauad, Hélder; Rodrigues, Lívia Carla Silva de Melo; Cunha, Cláudio da; Barros, Daniela Martí
The prefrontal cortex (PFC) is thought to be the anatomical site for working memory. Its medial region (mPFC) receives massive dopaminergic projections from ventral tegmental area through the mesocortical dopaminergic pathway. Dopaminergic activity is highly related to working memory function and the modulation of N-methyl-D18 aspartate (NMDA) receptors seem to be critical in these processes. Thefore, this study investigated the involvement of dopamine D1 receptors and its interaction with NMDA receptors in the medial prefrontal cortex (mPFC) on spatial working memory. Male Wistar rats with bilateral cannulae implanted in the mPFC (B: + 2,5 mm AP; +/- 1 mm L; - 2,7 mm V) were trained in the radial maze procedure and received intracortical administrations of the D1 selective agonist, SKF38393 [SKF: 0 (SAL); 0,56; 1,8; 5,6 µg], or D2/D4 antagonist, clozapine [0 (HCl 0,05N); 0,32; 1,0; 3,2 µg] , 10 min before the administration of MK-801 [MK: 0 (sal); 0,32; 1,0 or 3,2 µg]. After 5 min, animals were tested in 1-h delayed tasks in the radial maze. The effect of the administration of the D1 selective antagonist, SCH23390 [SCH: 0 (SAL) or 1,0 µg] before the SKF (0; 0,56 or 1,8µg), was also investigated. The D1 selective agonist, SKF produced, however, a significant (P < 0,01) increase in number of errors in small doses (0,56 e 1,8 µg) as compared to saline in the 1-h post-delay performance (mostly by reentry of arms visited in the pre-delay performance). This result suggests that the acute activation of D1 receptor located in mPFC impairs the long-term visuospatial working memory. The non-competitive antagonist of NMDA receptor, MK, disrupted the animals performance only at 1,0 µg dose (P < 0,05) (mostly by reentry of arms visited in the pre-delay performance). The lowest and highest dose did not differ from the control. This result suggests that the NMDA receptor blockade promotes an inverted U shaped modulation on working memory. SKF-38393, but not SCH-23390, administered into the mPFC increased the number of errors (mostly by reentry of arms visited in the pre-delay performance) in the 1-h post-delay performance at doses of 0.56 or 1.8 µg, but not at the highest dose. SCH-23390 1.0 µg blocked and MK-801 1.0 µg reversed the disruptive effect of SKF-38393 0.56 or 1.8 µg. The atypical antipsychotic, CZP, an antagonist of D2 and D4 receptors, did not alter working memory. Otherwise, their combination at 3,2 µg dose with 1,0 µg of MK increased the number of errors (mostly by reentry of arms visited in the pre-delay performance) as compared to the control treatment (P < 0,05) and also to others doses of CZP (0,32 and 1,0 µg) (P < 0,05). These results suggest that the blockade of D2 /D4 and NMDA receptors, simultaneously, are implicated in the impairment of this cognitive process. These results show that dopamine D1 receptors activation in the mPFC may disrupt the retention and/or recall of information in long-term delay. This impairment was blocked by dopamine D1 receptors antagonist and reversed by a non-competitive NMDA receptor antagonist, suggesting that dopamine D1 receptors and their interaction with NMDA receptors in the mPFC are crucial for adequate spatial working memory processing.
Efeitos do fator estimulador de colônias de Granulócitos (g-csf) sobre a hipertensão renovascular em Camunongos
(Universidade Federal do Espírito Santo, 2008-09-12) Nogueira, Breno Valentim; Meyrelles, Silvana dos Santos; Vasquez, Elisardo Corral; Bissoli, Nazaré Souza; Arruda, Robéria Maria Mandes Pontes; Silva, Valdo José Dias da
Background: The hematopoietic cytokine granulocyte colony-stimulating factor (GCSF) is a critical regulator of myeloid progenitor cell proliferation, differentiation and survival. And also, causes a marked increase in the mobilization of hematopoietic stem cells into the peripheral blood circulation. Recently, several studies regarding the effect of G-CSF attenuate renal injury during episode of acute ischemia-reperfusion. Aims: To evaluate the effects of G-CSF treatment into renal and cardiovascular system of mice with two-kidney, one-clip (2K1C) hypertension. Methods: Male C57 mice received a clip (0.12 mm) on the renal artery to induce renovascular hypertension (C57-2K1C, n = 32). All groups received G-CSF (100 µg/kg/day, SC) for 14 days since the operation. After treatment, the hemodynamic parameters were measured in conscious animals. At the end of the experiment the sample blood was collected and animals were euthanized in CO2 chamber. Also, the kidneys, hearts and others organs were excised, drained, and weighed. All values are expressed as mean±SEM. Two-way ANOVA was used to detect differences within each experimental group followed by post hoc Fisher test. Student’s t-test for independent samples was used when appropriate. Statistical significance was defined as p<0.05. Results: The animals 2K1C G-CSF showed that mean arterial pressure was lower than observed in 2K1C vehicle (129±2** mmHg vs. 150±5 mmHg, n=8). The clipped kidney/ contralateral kidney ratio showed a less atrophy of the ischemic kidney in treated group (0.50±0.02 vs. 0.66±0.01*). In addition, the histopathological analyses of kidney reveal a minor kidney infarct area with G-CSF use. The levels of plasma angiotensin I, II and 1-7 showed elevation in 2K1C vehicle when compared to sham group. However, we observed down levels of angiontensin I and 1-7 in 2K1C treated group. The infarct areas include 54% of all clipped kidney area, this areas reduced to 14% with G-CSF treatment. Conclusion: In conclusion, our data indicate that G-CSF administration prevents the kidney infarct and attenuate the high arterial blood pressure in 2K1C hypertensive mice, reinforcing the protect role of G-CSF on the kidney ischemia.
Efeitos cardiometabólicos da mobilização de gordura subcutânea induzida por ultra-som terapêutico: evidências de um modelo de síndrome metabólica em ratas
(Universidade Federal do Espírito Santo, 2008-10-31) Gonçalves, Washington Luiz Silva; Moysés, Margareth Ribeiro; Santos, Maria José Campagnole dos; Nunes, Maria Tereza; Mill, José Geraldo
Recent studies demonstrate that the ultrasound therapy increase adrenergic activity in the white adipose tissue (WAT), and produces local lipolysis with relevant fat corporal mobilization, currently effect described as ultrasound lipoclasia (USL). The aim of the present study was to investigate whether the peripheral USL can predispose to the development of metabolic syndrome components. Thirty female Wistar healthy rats (3 mo old) weighing ≈ 300g, were divided into sham-stimulated (SHAM, n=10), ultrasound-stimulated (LIUST, n=10), and washout-stimulated (WASHOUT) groups. An ultrasonic irradiation of 3 MHz was applied at the gluteusfemoral region in LIUST and WASHOUT groups. The spatial average and temporal average intensity ISATA was 5.6W/cm2 , pulsed mode 2ms: 8ms for 3 min during 10 days to produce local fat mobilization Anthropometrical, body composition, biochemical and hemodynamic parameters, and isolated heart studies were performed. All values are expressed as mean ± SEM. One- or two-way analysis of variance (ANOVA) followed by Tukey test was used for statistical analysis. The significance level was set at * p<0.05, **p<0.01, vs. group SHAM and # p<0.05, ##p<0.01, vs. LIUST group. In 10º day, the fat mass (38±1, 31±1** and 44±2*## %), mean arterial pressure (99±2, 121±2** and 100±1## mmHg), insulin (1.4±03, 3.3±0.05** and 3.1±0.2** µU/mL), triglyceride (25±3, 50±2** and 35±4*## mg/dL), and plasma glucose (141±13, 208±7** and 108±00# mg/dL) were verified in SHAM, LIUST and WASHOUT animals, respectively. The groups LIUST and WASHOUT also presented changes of the plasma inflammatory response and coronary dysfunction with impairment of adenosine-induced vasodilation (-14±2, -3±2** and -9±2*# 19 mmHg). These results show that not visceral only, but peripheral fat mobilization by USL leads to the development of the metabolic syndrome components with coronary dysfunction, being able to be a suitable model for studies in metabolic syndrome in adult females.
Estrogênio e progesterona modulam a expressão da proteína da Na+-K+-ATPase e do canal de sódio CNGA-1 em rins de ratas
(Universidade Federal do Espírito Santo, 2008-11-21) Graceli, Jones Bernardes; Morales, Marcelo Marcos; Moysés, Margareth Ribeiro; Oliveira, Maria Souza de; Bissoli , Nazaré Souza; Abreu, Gláucia Rodrigues
Estrogen (E2) and progesterone (P4) are both steroids hormones and they are involved mainly in the control of female reproductive functions. Among other effects, E2 and P4 can modulate Na+ reabsorption along the nephron altering the body hydroelectrolyte balance. The female hormones can modulate corporal Na+ balance by alterations of ion channel and ion pumps expressions and activities. In this work, we studied the possible involvement of E2 and P4 in modulating the expression and function of Na+ -K+ -ATPase pump and sodium channel CNG-A1 in the kidney of female Wistar rats subjected to ovariectomy with or without near-physiological 17b-estradiol benzoate and progesterone treatment for 10 days. The CNGA-1 and Na-K-ATPase protein expression from cortex and medulla renal were analyzed by Western blot. The decreased renal cortex expression of CNGA-1 and Na+ -K+ -ATPase protein observed in OVX group was restored to control levels after treatment with doses of estradiol and progesterone. The Na+ ,K+ -ATPase activity in renal cortex decreased in 50% in OVX group and the replacement of estradiol or progesterone in OVX animals increased those parameters to control group values. The other hand, there was no significant variation of, CNGA-1 protein expression, Na+ ,K+ -ATPase protein expression and activity in the medulla renal tissue of animals subjected to the same treatment. The 17b-estradiol added to cell culture medium significantly increased rat renal culture proximal tubule cell CNG1-A protein expression and Na+ ,K+ -ATPase protein expression and activity of control levels. The indirect immunofluorescence microscopy of the female adult rat kidney labeled with anti-sodium channel-CNG1-A antibody revealed that CNG1- A was expressed in the basolateral membrane of proximal and distal connecting 16 tubules. The reactivity to this antibody was only seen in kidney cortex. No immunofluorescence was detected in kidney medulla. This results suggest that Na+ -K+ -ATPase and CNGA-1 would be included in the family of transporters stimulated by estrogen and progesterone in the kidney and it might have an important role in renal function and that Na+ -K+ - ATPase and CNGA-1 subunit would be function relation in reabsorption of sodium in the proximal tubules.
Efeitos da exposição crônica ao cloreto de mercúrio (HgCl2) sobre a reatividade vascular e propriedades mecânicas e estruturais de artérias de resistência de ratos
(Universidade Federal do Espírito Santo, 2008-12-12) Peçanha, Giulia Alessandra Wiggers; Alonso, Ana Maria Briones; Vassallo, Dalton Valentim; Moreira, Cleci Menezes; Stefanon, Ivanita; Massaroni, Leila
Mercury produces toxic effects in both central nervous system and kidneys but its cardiovascular effects are not well explored yet. Among the toxicity mechanisms suggested an increase of oxidative stress has been proposed. This study analyzed the effects of chronic exposition to low concentrations of HgCl2 in endothelium-dependent responses of resistance arteries. Mesenteric resistance (MRA) and basilar arteries from 3-month old Wistar rats daily treated with HgCl2 (1st dose 1.3 µg, subsequent doses 0.02 µg, i.m) or vehicle by 30 days were used. Plasma mercury levels were determinated by Atomic Absorption Spectrometry and systolic blood pressure (SBP) by tail cuff. Vascular reactivity and structure of arteries were studied by wire myography and pressure myography respectively. Protein expression was evaluated by Western Blot and gene expression by RT-PCR. Superoxide anion (O2 •- ) levels were determined by dihydroethidium fluorescence, plasmatic malondialdehyde (MDA) levels by thiobarbituric acid assay and total antioxidant status by a commercial kit. Mercury plasmatic levels after 30 days of treatment were 29.2 ± 2.15 nM. Mercury treatment did not affect SBP, but increased phenylephrine contractile response, reduced acetylcholine (ACh)-induced vasodilatation and did not change the vasodilatation to the nitric oxide donor DEA-NO (10 nM-10 µM) in MRA. Mercury treatment also increased serotonin (5-HT) contractile response in basilar arteries. Endothelium removal and the NO synthase inhibitor (L-NAME, 100 µM) increased phenylephrine response only in control rats. Coincubation with L-NAME plus superoxide dismutase (SOD, 150 U/ml) on the HgCl2 group restored the effect of L-NAME in contractile response to phenylephrine and the SOD reversed the HgCl2 effect in basilar arteries. SOD, the hydrogen peroxide scavenger, catalase (1000 U/ml) or the NADPH oxidase inhibitor, apocynin (0.3 mM) restored the impaired ACh-induced vasodilatation in treated rats. The incubation with TEA, an inhibitor of K+ channels, increased the sensitivity to phenylephrine in control but did not modify the response in HgCl2 group. Indomethacin and tranilcipromine incubation did not alter the sensivity or maximum response to phenylephrine. Vascular superoxide anion production, eNOS expression, plasmatic MDA levels and total antioxidant status increased by HgCl2 treatment. However, SOD isoforms expression, COX and NOX gene expression remained unchanged. The HgCl2 treatment reduced the MRA wall thickness but increased its lumen diameter. These results suggest the chronic administration of low concentrations of HgCl2 increases the vascular reactivity to phenylephrine/serotonin, promotes endothelial dysfunction and alters the structure of MRA. This impairment of vascular function seems to be due to NO decreased bioavailability by increased O2 production from NADPH oxidase.
Efeito da doença peridontal sobre a reatividade vascular de camundongos ateroscleróticos (APOE-/-)
(Universidade Federal do Espírito Santo, 2008-12-15) Pereira, Raquel Binda; Stefanon, Ivanita; Meyrelles, Silvana dos Santos; 1º membro da banca
Periodontal disease was induced in mice by oral Porphyromonas gingivalis (Pg) inoculation to compare changes in vascular reactivity from animals without atherosclerosis (C57BL/6), animals with moderate atherosclerosis (ApoE) and animals with advanced atherosclerosis (ApoE D). The alveolar bone resorption was similar between the groups (P>0,05). In vitro preparations of mesenteric arteriolar bed were used to determine the vascular responses to acetylcholine, sodium nitroprusside and phenylephrine. Acetylcholine and sodium nitroprusside – induced relaxation were similar in the all groups (P>0,05). The maximal response to phenylephrine increased in the all groups, when compared to controls (C57 CT: 78,6 ± 2,7 vs C57 Pg: 92 ± 5,5; ApoE CT: 98 ± 5 vs ApoE Pg: 119 ± 6,5; ApoE D CT: 97 ± 7 vs ApoE D Pg: 120 ± 6 mmHg; P<0,05). This study demonstrates that periodontal disease increases the reactivity to phenylephrine in mice systemically healthy, with moderate atherosclerosis and with advanced atherosclerosis. Additionally to increased reactivity to phenylephrine, the periodontal disease exacerbated the systemic inflammation in mice with advanced atherosclerosis (neutrophils/lymphocytes ratio. ApoE D CT: 0,30 ± 0,04 vs ApoE D Pg: 2,37 ± 0,23, P<0,05).
Efeitos de uma única sessão de exercício resistido na contratilidade miocárdica e na reatividade vascular de ratos espontaneamente hipertensos.
(Universidade Federal do Espírito Santo, 2008-12-18) Lizardo, Juliana Hott de Fúcio; Vassallo, Dalton Valentim; Stefanon, Ivanita; Meyrelles, Silvana dos Santos; Rossoni, Luciana Venturini; Simões, Herbert Gustavo
The regular exercise elicits beneficial adaptations in the cardiovascular system, for example reducing resting arterial pressure (AP) and improving vascular and ventricular function. Recently, we investigated the effects of acute exercise after a single bout. After a single endurance exercise session a decrease of resting AP and of vascular reactivity occurs. However, the underlying mechanisms of cardiac and vascular effects evoked by a single resistance exercise (RE) session are unknown. Therefore, the aim of the present study was evaluate the AP, myocardial contractility and vascular reactivity after a single RE session. Spontaneously hypertensive rats (SHR) with 3 months of age weighting 250-300 g were used. The AP was measured in conscious animals. In vitro, we evaluated the tail and aortic vascular contractile responses, the contractility of papillary muscles of left ventricle (LV) and of the isolated heart perfused by the Langendorff technique after an acute RE, in 2 experimental groups: control (Ct) and exercise (Ex). The animals were exercised in an apparatus described previously by Tamaki e cols. (1992). A single RE session caused pronounced decrease of systolic and diastolic AP when compared to pre-exercise conditions (∆ - 79 ± 1.8; - 23 ± 2.3 mmHg, respectively; P<0.05). In the tail artery, the vasodilator response induced by acetylcholine increased the sensitivity (EC50) of dose-response curve in Ex animals (EC50 = 9.8 ± 0.06 log M, P<0.05) when compared to Ct animals (EC50 = 8.7 ± 0.1 log M). The maximal response (Rmax) to phenylephrine decreased after the exercise session (Ex: 276 ± 22 mm Hg vs. Ct: 439 ± 18 mm Hg, P<0.05). This response was abolished after endothelial damage, as well as after L-NAME and indomethacin administration. In aortic rings, the exercise decrease the EC50 (Ex= -5.9 ± 0.07 vs. Ct= -5.3 ± 0.06 log M; P<0.0001) and the Rmax to ACh (Ex= 53 ± 1.6 % vs. Ct= 73 ± 1.5 %; P<0.0001). These responses were abolished in presence of an adenosine receptor antagonist (EC50: Ex= -5.9 ± 0.07 vs. Ct= -5.3 ± 0.06 log M; P<0.0001. Rmax: Ex= 53 ± 1.6 vs. Ct= 73 ± 1.5 %; P<0.0001). The Rmax to FE was reduced after exercise (95 ± 7.9 % vs. Ct 120 ± 4.2 %; P<0,008). This reduction was abolished after endothelial damage and after L-NAME administration. The exercise increased the force development of isolated papillary muscles (Ex: 1.0 ± 0.1 vs. Ct: 0.63 ± 0.2 g/mg, P<0.05). In this preparation, the post-rest contraction (PRC) was greater in exercised animals (4.1 ± 0.4% g/mg vs. Ct: 1.7 ± 0.2% g/mg, P<0.05). Moreover, papillary muscles of exercised animals developed greater force with increasing isoproterenol concentrations (P<0.05). However, the contractile machinery activity evaluated by tetanic contraction was not altered after exercise (Ex: 0.24 ± 0.05 vs. Ct: 0.28 ± 0.05 g/mg, P>0.05). In the isolated perfused heart the exercise increased the left ventricle isovolumetric systolic pressure (LVISP) in baseline conditions (∆ +39 mmHg; P<0.05). Exercised rats presented a greater response to the Frank-Starling mechanism with the progressive increase of diastolic pressure (P<0.05). Under positive inotropic intervention to calcium and isoproterenol the LVISP was greater in Ex animals (P<0.05). The results obtained in the present study showed that a single RE session decrease the resting AP, improves the endothelial function and increases myocardial contractility in SHR.
Avaliação da circunferência da cintura como variável preditora de risco coronariano em estudo de base populacional
(Universidade Federal do Espírito Santo, 2008-12-19) Goncalves, Christine Pereira; Mill, José Geraldo; Benseñor , Isabela Judith Martins; Sichieri, Rosely; Rodrigues, Sérgio Lamêgo
INTRODUCTION: Coronary heart disease is one of the most prevalent disease in Brazil and it determines high morbidity and mortality rates. Simple and practical measure that can be used to the health professionals to detect subjects with high risk of coronary heart disease development can be important for its prevention and early diagnostic. In the last years, attention has been given to the rule of abdominal obesity in the development of chronic diseases, especially of the cardiovascular disease. In practice, direct assessment of fat amount is difficult. Therefore, waist circumference can be used as an anthropometric indicator of abdominal adiposity. OBJECTIVES: To evaluate the association between waist circumference and coronary risk factors; to analyze the WHO waist circumference cut-off point capacity to predict these risk factors; to determine the best waist circumference cut-off point to predict hypertension, diabetes, dyslipidemia and high coronary risk in the study sample. METHODS: This is a population-based, cross-sectional study carried out in Vitória city, with 1,662 subjects. Data collect was done using structured questionnaire. Anthropometric data, arterial blood pressure measurements and blood biochemistry data were also collected. Coronary risk was calculated using Framingham score. It was considerated high as it was greater than 20%. WHO waist circumference cut-off points were used as reference. Correlation analyzis, linear and logistic regression were carried out. ROC curve construction using the waist circumference as predictor variable for the coronary risk factors was done. The best waist circumference cut-off point was determined by the Youden index. RESULTS: 764 men and 898 women aged 25 to 64 years were studied. Correlation and regression analyses showed positive association between waist circumference and hypertension, diabetes, dyslipidemia or high coronary risk. In men, the waist circumference cut-off point recommended by WHO presented low or moderate sensitivity to detect the studied risk factors. In women, the perfomance of the point corresponding to 80 cm was moderate to good. Area under the ROC curve was greater than 0.5 for all risk factors. This shows that the waist circumference is able to identify hypertensive, dyslipidemic, diabetic and high coronary risk subjects. Data of this study suggest waist circumference cut-off points between 85 and 95 cm in men and between 76 and 90 cm in women to identify hypertension, dyslipidemia, diabetes and high coronary risk to be used in population with similar characteristics of this study. CONCLUSION: Waist circumference can be used as predictor of hypertension, dyslipidemia, diabetes and high coronary risk. Because it is a simple and practical measure and for it has easy interpretation, it is proposed that waist circumference can be used as a tool of epidemilogical vigilance for these outcomes.
Remodelamento vascular em artérias mesentéricas de resistência de camundongos diabéticos db/db
(Universidade Federal do Espírito Santo, 2009-02-13) Souza, Flavia Moreira; Ferreira, Carlos Mauricio de Carvalho; Padilha, Alessandra Simao; Pereira, Fausto Edmundo Lima
Little is known about Type 2 diabetes-induced structural remodeling of mesenteric resistance arteries. This study compared structural differences in small mesenteric resistance arteries in diabetic (db/db) and control (Db/db) mice. Vessels were isolated from 16wks old mice and structural properties were assessed by pressure myography. Mean arterial pressure (MAP) was measured in vivo by telemetry. The animals were treated for 4 wks with antioxidants Tempol or apocynin or with AT-1 receptor blocker candesartan. Western blot analysis was used to assess the expression of matrix regulatory proteins. MAP was similar between all the groups studied. Fasting blood glucose levels were higher in db/db mice (505±28 mg/dl) vs. control (115±10, p<0.001). The lumen diameter and media cross-sectional area were significantly increased in db/db compared to control suggesting hypertrophic outward remodeling. Cross-sectional compliance was significantly larger in the diabetic arteries. The stress-strain curve was shifted to the right in mesenteric arteries from diabetic mice compared with controls. Neither one of the treatments were able to change the remodeling presented by the db/db mice, as well as compliance and stress-strain relationship. The expression of the matrix regulatory proteins MMP-9, MMP-12, TIMP-1, TIMP-2, TGF-β and PAI-1 were increased in db/db arteries, while MMP-2 expression was not different between the groups. These data suggest that diabetic mesenteric resistance arteries undergo hypertrophic outward remodeling, increased vessel compliance and reduced stiffness that was associated with extracellular matrix turnover secondary to an imbalance between pro and anti-fibrotic factors. Neither the oxidative stress nor the pathways of angiotensin II in type II diabetes were involved at the remodeling or structural changes presented by diabetic db/db mice with 16wks of age treated for 4 wks.
A Exposição Crônica e Baixas Doses de Cloreto de Mercúrio Altera a Reatividade Vascular da Artéria Aorta de Ratos. Papel das Espécies Reativas do Oxigênio e dos Prostanóides da Via da Ciclooxigenase .
(Universidade Federal do Espírito Santo, 2009-05-07) Pecanha, Franck Maciel; Vassallo, Dalton Valentim; Stefanon, Ivanita; Pereira, Fausto Edmundo Lima; Cibin, Francielli Weber Santos
Mercury exposure produces toxic effects in central nervous system and kidneys. Recently these toxic effects were associated to cardiovascular events but the underlying mechanisms are not well explored. The main purpose of this study was to investigate if mercury exposure at low doses alters vasoconstrictor prostanoids production from cyclooxygenase-2 (COX-2) and its contribution to phenylephrine vasoconstrictor responses and acetylcholine vasodilator responses. For this were developed an experimental model of exposure to low doses of mercury chloride (HgCl2) and evaluated the effect of this exposure on systolic blood pressure (SBP), the participation of products derived from the endothelium, prostanoids derived from the cyclooxygenase-2 (COX-2), reactive oxygen species (ROS) and the reninangiotensin system in vascular reactivity in conductance arteries. Aortic segments from 3-month old Wistar rats daily treated with HgCl2 (1st dose 4.6 µg/kg, subsequent dose 0.07 µg/kg/day, i.m) or vehicle for 30 days were used. The vascular reactivity experiments were performed in an organ bath, the atomic absorption spectrometry for determination of blood concentration of mercury, RT-PCR and Western blot to verify the gene and protein expression, confocal microscopy analyzed levels of superoxide anion and structure of arteries. A commercial kit used to determine the production of prostanoids derived from COX-2 pathway. The activity of angiotensinconverting enzyme (ACE) was measured by fluorometry method and SBP by tail plethysmography. Blood levels of mercury at the end of treatment were 7.97 ± 0.59 ng/ml. Mercury treatment did not affect systolic blood pressure, but increased phenylephrine contractile responses, reduced acetylcholine-induced vasodilatation and did not change the vasodilatation by the nitric oxide donor, DEA-NO, in aortic rings. The contractile prostanoids derived from COX-2 pathway, reactive oxygen species (ROS) and increased plasmatic ACE activity were related to these responses. Increased production of EROS, increased plasma ACE activity, increased gene expression of mRNA for COX-2 and increased production of contractile prostanoids (PGE2 and TXA2) derived from COX-2 were observed in animals exposed to mercury and reinforce the hypothesis of a greater involvement of these pathways in the alteration of vascular response to phenylephrine. In the presence of superoxide dismutase (SOD) the vasodilator response to acetylcholine was improved in rats of the mercury group, indicating that endothelial dysfunction appears to be responsible for the increased production of EROS. The extracellular SOD (EC-SOD) expression was increased by exposure to mercury. These results suggest that this new experimental model of chronic exposure at low concentrations of HgCl2 promotes endothelial dysfunction due to the reduced bioavailability of NO induced by increased oxidative stress, and increase the contractile response to phenylephrine with greater involvement of the reninangiotensin system, EROS and contractile prostanoids derived from COX-2 pathway in this response. These results help to clarify the mechanisms by which mercury at low doses exerts toxic effects on the cardiovascular system and can be considered a risk factor for development of cardiovascular disease.
Influência do Gênero Sobre a Regurgitação Aórtica, Deposição Lipídica e Senescência Vascular em Camundongos Idosos Ateroscleróticos
(Universidade Federal do Espírito Santo, 2009-05-14) Pereira, Thiago de Melo Costa; Lima, Valter Correia de; Meyrelles, Silvana dos Santos; Vasquez, Elisardo Correal; Stefanon, Ivanita; Arruda ,José Airton
Although exhausting evidences have investigated age-related differences in cardiovascular performance, the impact of gender on such age-associated cardiovascular changes can be more explained. Such investigations would be important because the gender-related differences in cardiovascular aging may help to explain in part the greater longevity of women and of females of most of the mammalian species. Our aim was to investigate in aged mice morphophysiological alterations related to gender and dyslipidemia through the angiography, histological and enzymatic assays. We studied senescent mice of 18 months of age, separate in the groups: C57 (female: n=26; males: n=22; ovariectomized: n=10) and ApoE (female: n=28 and males: n=23; ovariectomized: n=7). After carotid catheterization, was realized the angiography for analysis of internal diameter (ID), aortic regurgitation (AR) and other parameters. Immediately after, the animals were submitted the histological or biochemical assays for detection of areas of lipid deposition (LD), vascular senescence (VS) and cholesterlemia. Statistical analysis was performed with Student's t or 1-way ANOVA followed by the Tukey post hoc test (*p<0,05). The angiography did not show significant differences between C57 and ApoE mice in relation to ID and aortic blood flow velocity (95,4 ± 6,2 vs 102 ± 5,7 mm/s, respectively). After the histological analysis, was confirmed the increase of external diameter in ApoE animals (2617 ± 149 mm2 ) when compared with C57 (1396 ± 159 mm2 , p<0,001). In the histochemical evaluation of aorta, only the male ApoE animals showed a significantly severity of LD (C57 female: 0.11 ± 0,01; C57 male: 0.12 ± 0,01; ApoE female: 0.21 ± 0,04 and ApoE male: 0.35 ± 0.05* cm2 ) and VS (0.01 ± 0.008, 0.016 ± 0.01, 0.025 ± 0.02 e 0.19 ± 0.08* cm2 , respectively)having a correlation with cholesterolemia of the C57 groups (female: 81 ± 4 vs. male: 96 ± 6 mg/dL) and ApoE groups (female: 336 ± 32* vs. male: 650 ± 92* mg/dL). It was a remarkable level of severity of AR in male compared with female both in C57 (female: 0.7 ± 0.24 vs. male: 3 ± 0.24*) and ApoE (female: 0.8 ± 0.2 vs.male: 2.3 ± 0.3*). We found a good correlation between valvular regurgitation and histologically assessed valvular thickness, without pathological or compensatory mechanisms. After 12 months, the C57 and ApoE ovariectomized females did not show difference in LD, VS, cholesterolemia or AR between respective female groups. Therefore, our data suggest an important participation of gender-related differences in cardiovascular aging, showing that endogenous/genetics factors can be essentials for development of cardiovascular diseases.
A disfunção ventricular direita pós-infarto do miocárdio está associada com o desenvolvimento da insuficiência cardíaca
(Universidade Federal do Espírito Santo, 2010-05-07) Fernandes, Aurélia Araújo; Zornoff, Leonardo Antônio mamede; Stefanon, Ivanita; Alessandra Simao Padilha; Vassallo, Dalton Valentim; Pereira,Fausto Edmundo Lima
Heart failure (HF) is the major cause of death and morbidity after myocardial infarction (MI) that can result in reduced cardiac output, increased venous pressure and cardiac remodeling. Usually, the left ventricle failing causes right dysfunction being related to greater risk of hospitalization. It has been suggested that assessment of right ventricle (RV) function is of important value to prognostic of HF after MI. Therefore, the aim of this study was to assess right ventricle contractility early (one week) and late phase (eight weeks) after MI. MI with signal of HF (HF group) and without signal of HF (Inf group) were compared to a sham-operated group (sham). Wistar male rats were anaesthetized with Ketamine (50 mg/kg) and Xylazine (5 mg/kg), i.m., and MI was induced through left coronary artery ligation at 3 mm of its origin. After 1 and 8 weeks the rats was anaesthetized with urethane (1.2 g/kg i.p.) and a catheter was inserted into the aorta and left ventricle to pressures measurements using a pressure transducer (TSD 104A) coupled to a Biopac MP100 system. Strips from the right ventricle were removed and attached to an isometric transducer and superfused at 30ºC with Krebs solution, stimulated at 0.5 Hz and 80 mV. The experimental protocols were approved by the local animal ethics committee (CEUA-EMESCAM). Both infarct groups presented same scar size (Inf 1 week= 32.4 ± 3; HF 1 week=33.7 ± 2.2; Inf 8 weeks= 26.5 ± 1.1; HF 8 weeks= 25 ± 0.9). The scar size did not have correlation with HF signals (left ventricle end diastolic pressure (LVEDP), increased lung weight and body weight ratio (LW/BW) and right ventricle to body weight ratio (RV/BW) neither with RV contractility. The LVEDP increased in HF group but not in the Inf group early (1 week: HF=15 ± 1*; Inf=5.2 ± 0.8; Sham=3,7 ± 0,6 mmHg) and late after MI (8 weeks: Hf=16 ± 2.5*, Inf- 7.5 ± 0.7; Sham= 5.2 ± 0.8 mmHg), *P< 0.05 ANOVA one way, post hoc Tukey. In the HF group LW/BW and RV/BW ratio was increased in the late phase, but not in the early phase after MI. The body weight was smaller in the HF group at 1 week, but similar to sham 13 and Inf 8 weeks after MI. Therefore, there was a negative correlation between force development in the RV strips and body weight in both early and late phase after MI. The inotropic responses to Ca2+ and Isoproterenol were preserved in HF group one week after MI and reduced at 8 weeks (8 weeks; CaCl2 2.5 mM: sham= 157 ± 18.4; Inf= 138 ± 17.3; HF= 62 ± 10.3 g/g P<0.05; Isoproterenol 10- 5 M: sham = 149 ± 14; Inf = 137 ± 18.7; HF = 58 ± 8.1 g/g P<0.05). Inversely, in the Inf group, the positive intropic response was reduced in the early phase and reduced in the late phase (1 week; CaCl2 2.5 mM: Sham= 186 ± 8.3; Inf = 135 ± 11.7; HF= 158 ± 13.1 g/g; P<0.05; Isoproterenol 10-5 M: Sham= 145 ± 9.9; Inf= 108 ± 10.8; HF= 166 ± 12 g/g P<0.05). The Ca2+ handling proteins expression (sarcoplasmatic reticulum calcium pump (SERCA-2a), phosfolamban (PLB total), PLB phosphorylated and Na+ /Ca2+ exchange) were not different among the groups in the early phase. But, in the late phase there was a SERCA-2a overexpression and an higher SERCA/PLB ratio just in the Inf group. In conclusion, the scar size did not correlate with HF signals neither with RV contractility. The RV dysfunction was found in the late phase after MI in rats with HF. However, the rats with HF maintain the RV function in early phase after MI. The infarct rats without HF maintained the RV contractility and increase SERCA-2a expression in the late phase after MI. The different inotropic βadrenergic response between the groups with and without HF could be induced by different mechanisms involving upregulation and downregulation of the βreceptors during the early and late phase after MI.
Eficácia dos exercícios de alongamento e de estabilização lombar no tratamentro de lombalgia crônica
(Universidade Federal do Espírito Santo, 2010-08-03) Maria Angelica Ferreira Leal Puppin; Marques, Amélia Pasqual; Futuro Neto, Henrique de Azevedo; Ferreira , Elizabeth Alves Gonçalves; Abreu, Glaucia Rodrigues de; Araújo , Maria Teresa Martins de
Low back pain affects over 70% of the population, mostly economically active adults. In addition to the high incidence, chronicity and disability makes this disorder a public health problem in industrialized countries. Kinesitherapy is the first line of choice in physical therapy, but there is no evidence of which type of exercise is more effective. The aim of this study, was to assess, the effectiveness of the GDS method on pain, functional disability, global flexibility and ability to contract the transverse muscle of abdomen (TrA) in individuals with chronic low back pain. 82 patients were randomized into three groups: Stretching (n = 30, age 37.5 ± 12.1) subjected to stretching exercises; Stabilization (n = 27, age 39.0 ± 12) which performed exercises to recruit the deep muscles of the lower trunk and Control (n = 25, age 37.8 ± 13.6) that were not treated. The intervention groups were treated with two weekly sessions lasting 40 minutes, for eight weeks. Pain was assessed by visual analogue scale; functional disability by the Oswestry Index, global flexibility by the third finger to the ground and the ability of TrA contraction by the pressure biofeedback unit. The variables were analyzed before, after and after eight weeks of treatment. We used the single-factor ANOVA with repeated measures and post hoc Holm-Sidak for parametric variables and Friedman's test and Tukey for non parametric at comparisons within and between groups. A significance level of 5% was employed. We also evaluated the relative clinical gain. The results showed significant improvement in pain, functional disability and overall flexibility after treatment and after eight weeks (p <0.05) in the intervention groups. Only the stabilization group was effective in improving the capacity of contraction of TrA (p <0.05). When comparing groups, the two forms of intervention were effective in reducing pain and functional disability (p <0.05). Nevertheless only the Stretching group showed significant improvement in global flexibility (p = 0.01) There was no differences between groups after eight weeks of treatment in functional disability (p = 0.10) and global flexibility (p = 0.07). There was no difference between groups in the ability of contraction of TrA in any of the times evaluated. The two experimental groups had gains on clinical relevance, especially the Stabilization group, except for global flexibility variable in which the stretching exercises had higher gains. The two treatments, stretching and lumbar stabilization used in GDS were effective in reducing pain, functional disability and improving global flexibility, but only the stabilization exercises showed improved ability of the contraction of the TrA in patients with chronic low back pain.
Efeitos da exposição crônica a baixas concentrações de cloreto de mercúrio (20 ηM) sobre o sistema cardiovascular de ratos
(Universidade Federal do Espírito Santo, 2010-10-05) Giuberti, Karina; Vassallo, Dalton Valentim; Sánchez, Mercedes Salaices; Stefanon, Ivanita; Futuro Neto, Henrique de Azevedo; Massaroni, Leila; Kalinin, Ana Lucia
Mercury is naturally present in earth's crust and it is inevitable, some degree of exposure during the whole life. It has been demonstrated a variety of pathological actions of mercury on the central nervous system, renal system and its association with increased cardiovascular risk. However, its toxic effects on the cardiovascular system under conditions of normotension and hypertension are not yet fully elucidated. In this study, Wistar and SHR rats (2.5 months old) were divided into four groups: control Wistar (Wistar CT) and control SHR (SHR CT) who received intramuscular injections of saline for 30 days or mercury (Hg Wistar) and (SHR Hg), which received 0.07 mg/kg/day HgCl2, the first dose was 4.6 mg/kg, reaching a final plasma concentration of about 29 ηM of mercury. At the end of treatment the following aspects were performed: assessment of weight, histological, hematological and biochemical profiles, measurements of hemodynamic parameters, angiotensin converting enzyme (ACE) activity and the production of malondealdeide (MDA) in the plasma of all animals. Chronic exposure to HgCl2 did not affect the weight and histological parameters when comparing Wistar CT vs Wistar Hg rats neither SHR CT compared to SHR Hg rats. In the hematological evaluation, the Wistar Hg rats showed a increased in platelet content (Wistar CT: 757 ± 55 vs Wistar Hg: 913 ± 20 103/µL) and neutrophils percentage (Wistar CT: 14 ± 5 vs Wistar Hg: 30 ± 4.3 %) and the percentage of lymphocytes decreased (Wistar CT: 83 ± 4.6 vs Wistar Hg: 68 ± 4.5 %), while in the SHR Hg, the percentage of neutrophils decreased (SHR CT: 45 ± 5.9 vs SHR Hg: 21.3 ± 4.8 %) and lymphocytes increased (SHR CT: 53 ± 6.5 vs SHR Hg: 76 ± 4.3 %). The glicemy values was increased in the Wistar Hg group (Wistar CT: 161.6 ± 12.3 vs Wistar Hg: 209 ± 15.4 mg/dL) meanwhile plasmatic globulin decreased (Wistar CT: 3.21 ± 0.09 vs Wistar Hg : 2.84 ± 0.1 g/dL). The systolic blood pressure, measured weekly by tail plethysmography, increased in rats in the fourth week of treatment (Wistar CT: 117 ± 3 vs Wistar Hg: 143 ± 5 mmHg). We also observed an increase in LV end-diastolic pressure of Wistar Hg rats (Wistar CT: 0.25 ± 0.4 vs Wistar Hg: 3.3 ± 0.5 mmHg). Treatment with Hg increased ACE activity in plasma (Wistar CT: 187.1 ± 16.2 vs Wistar Hg: 235.5 ± 14.2 ηmol/mL/min) and hearts of normotensive rats (Wistar CT: 3,4 ± 0.2 vs Wistar Hg: 4.1 ± 0.1 ηmol/mL/min/mg). In SHR Hg, ACE activity was increased in plasma (SHR CT: 113 ± 11.4 vs SHR Hg: 163 ± 15.8 ηmol/mL/min) and decreased in kidney (SHR CT: 80 ± 6.3 vs SHR Hg: 61.4 ± 2.8 ηmol/mL/min/mg), lung (SHR CT: 87.6 ± 2.2 vs SHR Hg: 75 ± 4 ηmol/mL/ min/mg), heart (SHR CT: 17.9 ± 1.1 vs SHR Hg: 14.8 ± 0.58 ηmol/mL/min/mg), brain (SHR CT: 40.3 ± 2.3 vs SHR Hg: 27.8 ± 1.8 ηmol/mL/min/mg) and aorta (SHR CT: 670 ± 16.3 vs SHR Hg: 535 ± 19.2 ηmol/mL/min/mg). The involvement of oxidative stress was assessed indirectly by measuring the production of MDA, which was found increased in the Wistar Hg rats in both plasma (Wistar CT: 0.93 ± 0.06 vs Wistar Hg: 1.28 ± 0.18 mM) and in heart (Wistar CT: 0.22 ± 0.01 vs Wistar Hg: 0.28 ± 0.01 mM) and decreased in the kidney (Wistar CT: 0.38 ± 0.03 vs Wistar Hg: 0.14 ± 0.01 mM). In SHR Hg rats, this production was increased in heart (SHR CT: 0.45 ± 0.02 vs SHR Hg: 0.55 ± 0.02 mM) and aorta (SHR CT: 0.96 ± 0.11 vs SHR Hg: 1.51 ± 0.14 mM) and decreased in the lungs (SHR CT: 0.21 ± 0.01 vs SHR Hg: 0.12 ± 0.01 mM), kidney (SHR CT: 0.96 ± 0.03 vs SHR Hg: 0.51 ± 0.01 mM) and brain (SHR CT: 0.54 ± 0.03 vs SHR Hg: 0.34 ± 0.01 mM). These results suggest that chronic exposure to mercury even at very low concentrations interferes with the activity of angiotensin converting enzyme and production of free radicals. Also it alters the levels of the blood glucose, platelet, immune, systolic blood pressure, and left ventricular end diastolic pressure. The results isolated or interconnected, can contribute to the understanding of various diseases related to contamination with metal. It can be conclude that such exposure represents a risk factor for developing of cardiovascular disease in normotensive animals (Wistar) and it may represents a aggregating factor of pre-existing risks to hypertensive rats (SHR).
Avaliação cardiorrespiratória em ratos submetidos à convulsão por eletrochoque
(Universidade Federal do Espírito Santo, 2010-10-28) Furtado, Danielly Peres; Mauad, Helder; Cabral, Antônio de Melo; Antonio Carlos Avanza Junior; Vassalo, Dalton Valentim; Calil, Osmar Araújo
The aim of this study was to evaluate the cardiopulmonary changes after induction of electroshock seizures (ES) in rats. We used 113 Wistar rats weighing 250-350g. Under anesthesia, we performed implantation of ears electrodes for the induction of ES and catheterization of the femoral vessels to allow cardiovascular recordings. Measures of mean arterial pressure (MAP) and heart rate (HR) were made before and after 0.3, 2, 5, 10, 15, 20, 25 and 30 minutes post-ES in awaked animals. Respiratory rate (RR), tidal volume (VT) and pulmonary ventilation (Vmin) were evaluated before and after the induction of ES, using the technique of whole-body plethysmographic chamber. The autonomic components were assessed by blockade of β1-adrenoceptors with atenolol and muscarinic colinoceptors with methyl-atropine. The cardiovascular reflexes were assessed by injection of potassium cyanide (KCN) (chemoreflex); fenilbiguanide (FBG) (Bezold-Jarisch reflex) and sodium nitroprusside and phenylephrine (baroreflex). The effects of sino-aortic denervation (SAD) and peripheral adrenergic blockade with atenolol and prazosin (α1-adrenergic antagonist) on responses to induction of ES were also evaluated. The results showed a significant increase in MAP at 0.3 and 2 minutes postES (134 ± 6 and 123 ± 5 mmHg, respectively) compared to control values pre-ES (100 ± 2 mmHg). There were no significant differences among other moments. For baseline HR, compared to control values pre-ES (392 ± 8 bpm) a significant reduction was observed (p<0.01) at 0.3 minutes after electroshock. A significant reversal of HR was observed after 15 (446 ± 13 bpm), 20 (454 ± 10 bpm), 25 (470 ± 7 bpm) and 30 (477 ± 7 bpm) minutes post-ES compared to control values. Regarding the autonomic components (sympathetic and parasympathetic) we observed that the ES caused a significant increase in parasympathetic activity during the post-ictal period (1 minute), followed by a progressive attenuation of this component at 2, 5, 10, 20 and 30 minutes post -ES. In relation to the sympathetic component, we initially observed a progressive increase since from one minute after the ES, which was statistically significant at 5 (17 ± 2* bpm), 10 (26 ± 5** bpm) 20 (34 ± 6** bpm) and 30 (45 ± 6** bpm) minutes after the electroshock when compared to the first minute (-2 ± 2 bpm). After double blockade with atenolol and methyl-atropine, we observed significant increase (p<0.01) in the MAP values after 1 (156 ± 2 mmHg) and 2 (135 ± 6 mmHg) minutes after ES when compared to control values (97 ± 4 mmHg). There was no significant difference among the MAP values at 5, 10, 20 and 30 minutes after the ES and control values. Regarding the respiratory parameters, it was observed apnea during ictal and post-ictal periods in 78% of animals. In addition, there was significant increase of the VT values (p<0.01) at 0.3 (11.4 ± 0.6) and 2 (12.2 ± 0.8) minutes after ES compared to the control (7.1 ± 0.3). In relation to the RR, there was a significant reduction (p<0.01) at 0.3 minutes (67 ± 3 cam) compared to control (97 ± 6 cam). In the same way, in relation to Vmin we observed a significant increase (p<0.01) only at 2 minutes after the induction ES (1249 ± 120) compared to the control (677 ± 36). To the chemoreflex, we observed that KCN produced pressor responses (48 ± 3 mmHg), which was significantly reduced after the induction of ES at 1 (33 ± 4 mmHg) and 5 (34 ± 4 mmHg) minutes compared to control (48 ± 3 mmHg). There was no statistical difference among the other moments after the ES. With regard to HR chemoreflex, there was significant reduction in the first minute post-ES (-106 ± 9 bpm) when compared to control (-194 ± 11 bpm), however, this response was significantly higher compared to control group at 5 (- 263 ± 13 bpm), 10 (-262 ± 16 bpm), 20 (-274 ± 16 bpm) 30 (-253 ± 16 bpm) minutes after the induction of ES. With regard to the Bezold-Jarisch reflex, it was observed initially that the injection of FBG produced hypotensive (-48 ± 2 mmHg) and 22 bradycardic (-248 ± 11 bpm) responses. These hypotensive responses were not statistically different from the control after the induction of ES. In relation to bradycardic response, we observed a significant attenuation in the first minutes after the ES, i.e., at 0.3 (-157 ± 16 bpm) and 2 (-110 ± 16 bpm) minutes when compared to control values (- 248 ± 11 bpm). There were no significant differences in the remaining moments after the ES. Regarding the baroreflex, we observed that only the gain measured in response to bradycardia phenylephrine-induced for 2 minutes after induction of ES was significantly attenuated. After SAD, there was significant attenuation of the bradycardic response induced by ES, which was also observed in the group submitted to blockade with atenolol+prazosin. The results of this study suggest that the tonic-clonic seizures induced by electroshock produced major changes in the: a) cardiovascular system, characterized by hypertensive and bradycardic responses, b) respiratory system, characterized by apnea, hyperpnea and bradypnea observed immediately after induction of ES, c) a significant impairment of the cardiovascular reflexes responses (chemoreflex, BezoldJarisch reflex and baroreflex), d) autonomic dysfunctions observed in the ictal period, in which we observed a significant increase of the cardio-vagal and sympathetic vascular autonomic activities. In the post-ictal period, only an increased cardiac sympathetic activity was observed. Thus, at least in part, this cardio-vagal response is mediated by arterial baroreceptors.

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