Ciências Fisiológicas

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Remodelamento vascular em camundongos ateroscleróticos na coexistência de hipertensão renovascular 2R1C
(Universidade Federal do Espírito Santo, 2005-05-31) Nogueira, Breno Valentim; Meyrelles, Silvana dos Santos; Vasquez, Elisardo Corral; Redins, Carlos Alberto; Ricardo, Kelly Fabiane Santos
ApoE-/- knockout mouse is a model for studies of hypercholesterolemia, which is characterized by developing atherosclerotic lesions mainly in great arterial vessels such as the aortic arch, which is a site of baroreceptor nerve endings. In addition, it is known that angiotensin affects the atherosclerotic process and baroreflex sensitivity. Thus, the aim of this study was to evaluate morphological changes in the aortic arch in ApoE-/- mice with renovascular hypertension. Male (12-14 weeks old) C57 and ApoE-/- mice received a clip (0.12mm) on the renal artery to induce renovascular hypertension (C57-HT, N=11; ApoE-HT, N=11) and were compared with age-matched sham mice (C57-Sham, N=11; ApoE-Sham, N=11). After 28 days, mean arterial pressure (MAP) measured in conscious animals was higher in C57-HT and ApoE-HT (128±3 and 126±3 mmHg) than in their respective controls (103±2 and 104±2 mmHg, p<0.05). The animals were euthanized and perfused with a fixative solution at pressure equal to the MAP observed in each animal. The cross section area of the aortic arch was greater in C57-HT and ApoE-HT (0.76±0.05 and 0.73±0.03 mm2) than in their respective controls (0.64±0.02 and 0.63±0.03 mm2, p<0.05). The wall vessel area was also greater in these hypertensive groups (0.18±0.01 and 0.19±0.01 mm2) than in the normotensive groups (0.15±0.01 and 0.17±0.01 mm2, p<0.05). Consequently, the lumen vessel area followed the same results. In conclusion, our data indicate that at least at the early stage of atherosclerosis the remodeling process is not yet observed in the ApoE-/- mouse. Renovascular hypertension by itself leads to a positive remodeling of the aortic arch, which is aggravated by the association with atherosclerosis when compared with the C57 control.
Agentes infecciosos associados à diarréia aguda em crianças até três anos de idade : estudo em um hospital de referência no município de Vitória-ES
(Universidade Federal do Espírito Santo, 2005-10-14) Sadovsky, Ana Daniela Izoton de; Pereira, Fausto Edmundo Lima; Spano, Liliana Cruz; Leite, José Paulo Gagliardi; Morais, Mauro Batista de
Acute diarrhea is one of the main causes of infantile mortality worldwide (WHO), mainly in developing countries. In the present work, the prevalence of Rotavirus (RV), adenovirus (Ad), diarrheogenic E. coli (EPEC, ETEC, EIEC, EHEC, EAEC, DAEC), Salmonella, Shigella, Cryptosporidium spp., Entamoeba histolytica and Giardia lamblia was studied among children up to 3 years old with acute diarrhea. From February 2003 to June 2004, stools samples were obtained prospectly from 253 children with acute diarrhea and 78 without diarrhea attending to the emergency room in a pediatric hospital - Hospital Infantil Nossa Senhora da Glória (HINSG), in Vitória Espírito Santo state, Brazil. Bacterial detection was done in 241 stools samples (12 were excluded because were in use of antimicrobian drugs) and E. coli were isolated in 219 and 68 cases with and without diarrhea, respectively. These cases were submited to serology with policlonal anti-seros (EPEC e EIEC) and hybridization tests (Hybr) to detect virulence genes of EPEC, ETEC, EIEC, EHEC, EAEC e DAEC. RV were studied in 147 cases for immune enzymatic assay (EIARA) and in 230 cases by poliacrylamide gel electrophoresis (PAGE) and Ad, only in 147 cases for immune enzymatic assay (EIARA). Protozoan infection was studied in 88 cases for immune enzymatic assay (EIA). Children with diarrhea were divided in Group I (88 cases = all enteropathogens studied), Group II (147 cases = bacterias, RV e Ad - EIARA) and Group III (230 cases = bacterias and RV - PAGE) and children without diarrhea were Group IV (78 cases = bactérias and RV - PAGE). Enteropathogens were detected in more than 60% in children with acute diarrhea and bacterial infection was the most prevalent: DEC were detected in 41,1%; EPEC in 3,6% (serology) e 9,1% (Hybr); Typical EPEC (0,9%); Atypical EPEC (8,2%); EAEC (9,1%); DAEC (20,6%); EIEC (0,9%); ETEC (4,2%). In stools samples from children without diarrhea, we found Atypical EPEC (10,3%); EAEC (20,6%); DAEC (16,2%); ETEC (1,5%). EHEC was not detected in the studied population. Shigella and Salmonella were detected in 4,6% e 2,9%, respectively, only in children with acute diarrhea. RV were detected in 35,2% (GEPA) and 50% (EIARA); Ad, in 8,2% and E. histolytica, Cryptosporidium spp. and G. lamblia in 8%, 11,4% and 14,8% of cases with diarrhea, respectively. In conclusion, Typical EPEC, EIEC and ETEC were detected only or predominantly in children with acute diarrhea. Atypical EPEC, EAEC and DAEC were not causes of acute diarrhea, except for EAEC in children more than two years old (p = 0,026). RV was the most prevalent agent when the classic enteropathogen DEC (Tipical EPEC, ETEC, EIEC and Shigella e Salmonella) was considered in this study. RV was more frequent in children below 18 months of life and in a period of March, 2003 up September, 2003. Associations among enteropathogens were frequent in the studied population and protozoa were the most of them. Comparing all of protozoa detected, only G. lamblia suggesting being a cause of acute diarrhea, isolately.
Efeitos do aumento do fluxo expiratório sobre parâmentros cardiorrespiratórios de crianças com bronquiolite aguda
(Universidade Federal do Espírito Santo, 2005-12-16) Frasson, Thiago da Silva; Abreu, Glaucia Rodrigues de; Cabral, Antonio de Melo; Araujo, Maria Teresa Martins de
Acute bronchiolitis (BA) is an epidemic and seasonal respiratory infection of the child, who affects babies with age of up to two years. Chest phisioterapy has been wide used in the last years and considered a complement treatment of great aid in the prevention and treatment of pulmonary diseases in infancy. The bronchiolitis still is an illness little studied with the use of Chest phisioterapy techniques what in it comes across them with a at the very least controversial subject. The objective of this study is to verify the effect of the increase of the expiratory flow (AFE) in patients with BA, being evaluated props up it of Wood - Downes and the parameters of respiratory frequency (FR), cardiac frequency (FC), peripheral saturation of oxygen (SpO2), systolic arterial pressure (PAS), diastolic arterial pressure (PAD), average arterial pressure (PAM) in four different times, besides verifying social pointers through a partner-economic casuistry. The children had been randomized in 2 groups: experimental, where she was applied inhalation with medical lapsing, nasal hygiene and AFE, and has controlled group where she was applied inhalation and nasal hygiene. These parameters had been measured in four times: before the inhalation, immediately after the inhalation and before the application the AFE, immediately after the application of the AFE and thirty minutes after the application of the AFE. After the experiments the application of the comparative AFE to the group was observed a significant increase of the SpO2 (90,8947% to 97,2632%; p<0,5) in the experimental group thirty minutes has after controlled, that it did not have application of the maneuver, what in induces them to think that the AFE technique led in general to an improvement of the pulmonary function of these patients. We conclude thus that the technique of increase of the expiratory flow if shows efficient in the complement treatment of children with acute viral bronchiolitis.
Efeitos de diferentes terapias de reposição hormonal sobre a pressão arterial e balanço mineral ósseo de ratas castradas
(Universidade Federal do Espírito Santo, 2005-12-16) Véras, Wagner de Brito; Abreu, Glaucia Rodrigues de; Moysés, Margareth Ribeiro; Gouvêa, Sônia Alves
The estrogen has an important role in the homeostatic regulation of some tissues of the organism, good illustrated by the pathophysiologics alterations that occur in its deficiency, in the menopause. With the objective to brighten up these alterations, the use of the hormonal replacement therapy (HRT) in the aftermenopause has been studied, in function of its benefits in the prevention of osteoporosis and cardiovascular diseases. However, the traditional HRT with estrogen is associated with a bigger incidence in the development of cancer of breast and endometrium. One of the alternatives for the hormonal replacement is isoflavones (phytoestrogens derivatives of the soy) and the raloxifene (SERM). This study it has as objective to evaluate the possible effect of 17-β -estradiol, isoflavones and raloxifene on rats ovariectomyzeds throught of the measure of the arterial pressure, bone and plasmatic calcium and phosphorus concentration, corporeal, left ventricular and uterine weight. Adult Wistar rats had been divided in five groups (n=8). A group has controlled (C), a castrated group (CC) and the groups castrated and dealt with estrogen (CE), isoflavone (CI) and raloxifene (CR). Ten weeks after the ovariectomia, initiated the treatment of groups CE, CI and CR that lasted 12 weeks. In the end of the treatment, the direct measure of the pressure arterial and collected samples of blood was made, whose concentration of calcium and match had been measured. The animals had been, then, sacrificed to analyze the humid and dry weight of thighbone right and left, left ventricle and uterus, beyond the analysis of the concentration of calcium and match of thighbone. The treatment with 17-ss-estradiol, isoflavonas and raloxifeno did not modify the blood pressure levels of the rats. Groups CE and CR had gotten the lesser plasmatic levels and the biggest bone calcium levels. Group CR presented the lesser level of plasmatic match and groups CE and CR had presented the lesser levels of bone match. Group CE got the lesser profit of corporal weight. How much to the weight of thighbone, biggest groups CE and CR had gotten the profit of bone mass. The left ventricle presented bigger weight in group CE, as well as the weight of uterus. 15 On the basis of the gotten results, we conclude that the treatments with isoflavone and the raloxifene had presented greaters benefits, when comparative to the treatment with 17-ss-estradiol, therefore they had increased the calcium concentration and the bone mass without modifying the arterial pressure and nor the tropism of the cardiac and uterine cells
Angiotensina II intra-renal modula a expressão da óxido nítrico sintase neuronal na hipertensão renovascular 2R1C
(Universidade Federal do Espírito Santo, 2005-12-20) Pereira, Thiago de Melo Costa; Silva, Ian Victor; Meyrelles, Silvana dos Santos; Cabral, Antonio de Melo; Gouvêa, Sônia Alves; Soares, Luciana Saloto
In physiological conditions, nitric oxide (NO) exerts a modulatory influence on renal blood flow mainly due the neuronal nitric oxide synthase (nNOS) enzyme isoform. Although some studies have demonstrated that the renal nNOS mRNA expression is modified in arterial hypertension (HÁ), it has not yet been shown how nNOS protein expression is modulated by endogenous angiotensin II (Ang II), a vasoconstrictor and a NO function inhibitor. Through the western blotting technique have been evaluate the relative role of HA and Ang II on the nNOS protein expression in the kidneys of renovascular hypertensive rats two-kidneys one clip (2K1C). The specific aim was to investigate the role of AT1 receptors and oxidative stress in modulating nNOS expression and the NO bioavaiability by GMPc quantification for enzymeimmunoassay. Then, the animals were divided in 4 groups: 2K1C (n=9), 2K1C+subpressor dose of losartan (10 mg/Kg/day in drinking water; n=4), 2K1C+subpressor dose of tempol (0.2 mmol/Kg/day in drinking water; n=6), and Sham (n=16), presenting values of MAP 179 ± 5 mmHg, 140 ± 7 mmHg, 181 ± 10 mmHg and 99 ± 3 mmHg, respectively. The nNOS expression was increased in the contralateral and clipped kidneys of the animals 2R1C when compared to SHAM group (0,43±0,03 vs. 0,14 ± 0,02 u.d.o. e 0,27±0,03 vs. 0,16±0,03 u.d.o. respectively), normalized in both kidneys in 2R1C + losartan when compared to SHAM group (0,24 ± 0,01 vs 0,27 ± 0,01 u.d.o e 0,21 ± 0,03 vs.0,29 ± 0,02 u.d.o., respectively). In 2R1C + tempol group, the nNOS expression was decreased in the contralateral kidney (0,27 ± 0,06 vs. 0,19 ± 0,06 u.d.o., respectively) but still increased in the clipped kidney when compared to SHAM group (0,35 ± 0,08 vs. 0,17 ± 0,03 u.d.o., respectively). The present results demonstrate that: 1) In the 2K1C renovascular hypertension model, the AT1 receptors and oxidative stress seem to be primary stimuli for increasing nNOS expression but not the HA per se; 2) The increase in nNOS expression does not reflects directly on the more NO bioavaiability in both kidneys (contralaetral or clipped); 3) The increase in nNOS expression induces a compensatory mechanism in order to maintain the renal homeostasis in this model of hypertension.
Implante de tubo traqueal : modelo experimental para estudo das alterações cárdio-respiratórias observadas na hipertensão pulmonar
(Universidade Federal do Espírito Santo, 2006-01-01) Waichert Júnior, Élio; Mauad, Hélder; Fazan Júnior, Rubens; Vassallo, Dalton Valentim
The aims of this study were to evaluate cardiovascular, respiratory and gasometric changes in rats submitted to tracheal tube implantation and limitation of the chest. Under anesthesia, Wistar rats (240 – 270 g) were submitted to implantation of the one polyethylene tube (PE-90 with length of 8 mm) into the trachea for a period of 8 days and implantation of the rubber jacket around the chest to permit a certain limitation of expansion (JK+TTc group). Sham (ficticia surgery), TTc (rats submitted only to implant of PE-90 into the trachea) and JK-Sham (rats submitted only of the rubber jacket) animals were used as control. Are day before the recording period, under anesthesia, these animals had the femoral artery and vein canulated to permit cardiovascular, respiratory and gasometric recordings and drugs administration, respectively. Results showed a significant increasing in the basal heart rate (HR) in rats JK+TTc, as well as in the basal levels of the mean arterial pressure (MAP), systolic arterial pressure (SAP) and diastolic arterial pressure (DAP). In relation to respiratory parameters, these animals present a significant increasing in the respiratory frequency (RF), tidal volume (TV) and pulmonary ventilation (PV). In relation to the gasometric parameters, we observed a decrease of the partial pressure of oxygen (PpO2), increase of the partial pressure of carbon dioxide (PpCO2), reduction in the percentage of hemoglobin saturation and acidosis. It was also observed that these animals had a significant increase in the right ventricular weight, while the same it was not observed in relation to the left ventricle. In relation to cardiovascular reflexes, we observed that the animals JK+TTc present: a reduction in the baroreflex gain, an increase of chemoreflex pressor response in the dose of 10 and 20 µg/0.05 ml and an attenuation of the bradycardic response in dose of 40 and 80 µg/0.05 ml. In relation to Bezold-Jarisch reflex, we observed a significant attenuation of the hypotension and bradycardic responses. The evaluation of the autonomic components showed an increase in the sympathetic component and a reduction in the parasympathetic component. The role of the peripheral chemoreceptors was evaluated in 2 separated groups of animals: JK+TTc 1 day (animals submitted to tracheal tube implant plus chest jacket and were evaluated 1 day after the implantation) and JK+TTc PCR (animals submitted to tracheal tube implant plus chest jacket and removal of the peripheral chemoreceptors). We observed that the animals of the JK+TTc PCR grops presented RF and PV values significantly smaller than JK+TTc 1 day, while it was not observed a significant changes in TV between these groups. The animals of JK+TTc PCR present a significant reduction in the HR in relation the group JK+TTc 1 day, while a significant changes in MAP, SAP and DAP values were not observed among groups. The group JK+TTc PCR presented a significant decrease of the PpO2, pH and % of O2 Hbsaturation values and a significant increase in the PpCO2 and [H+] values in relation to the JK+TTc 1 day group. Our results suggest that the technique of tracheal tube implant plus chest limitation produces an important picture of pulmonary hypertension associated to a chronic hypoxemia and a several important cardiovascular and respiratory changes. The changes cited above and the possible repercussion result from the increasing air flow resistance, as well as pulmonary blood flow, constitute an important model for the study of pulmonary hypertension and also of the right ventricular hypertrophy (Cor pulmonale), as observed in these animals. These results also showed that the mechanisms of the cardiovascular regulation are significantly changed in the pulmonary hypertension, being the chemoreflex activation, a fundamental key the animals survival. We also observed that in this model of pulmonary hypertension, several cardio-respiratory parameters were already altered changed in the first day after the implants, whose alterations seems to be mediated mainly by peripheral chemoreceptors.
Diferença na contratilidade de ventrículos direito e esquerdo de ratos com e sem insuficiência cardíaca após o infarto do miocárdio
(Universidade Federal do Espírito Santo, 2006-04-10) Fernandes, Aurélia Araújo; Stefanon, Ivanita; Vassallo, Dalton Valentim; Bassani, José Wilson Magalhães
Coronary artery ligation is an experimental method used to induce myocardial infarction. The aim of this study was to analyze right and left ventricular performance in infarcted rats showing identical scar area. Infarcted rats with heart failure (INF-IC) were compared with asymptomatic rats (INF) and a control operated group (Sham). Eight weeks after surgery the scar area was similar between groups (INF= 26,5 ± 1,1 e INF-IC= 25 ± 0,9%). The left end diastolic pressure increased in the INF-IC group (16 ± 2,5 mmHg; p<0,05) but remained normal in the INF group (7,7 ± 0,7 mmHg) compared to Sham (5,2 ± 0,5 mmHg). Arterial and ventricular systolic pressures were similar in all groups. The increased right ventricular weight to body weight rate and the lung weight to body weight ratio differentiated rats with heart failure (INF-IC) from asymptomatic rats after infarction (INF) presenting same scar area. Isometric contractions from right ventricle strips (RV) and left ventricle papillary muscle were studied using a rate of stimulation of 0,5 Hz in Krebs solution at 30º C. Isometric force (normalized to muscle or strip weight, mg/g) in steady state condition was measured in the presence of [Ca+2]e (0,62; to 3,75 mM) and Isoproterenol (5x10-9 to 5x10-5 M) and during post rest potentiation. The positive inotropic response to calcium, Isoproterenol and post rest potentiation in the RV were preserved in the INF group but reduced in the INF-IC group (Ca2+ 3,75 mM: Sham= 163 ± 18 mg/g; INF= 148 ± 19 mg/g; INF-IC= 68 ± 11 mg/g; p<0,05); (Isoproterenol 5.10-5 M: Sham= 151 ± 15 mg/g, INF= 134 ± 17 mg/g, INF-IC= 52 ± 7 mg/g; p<0,05). The left ventricle papillary muscle contractile activity was reduced in both INF and INF-IC groups. These results demonstrate that myocardial infarction with same scar area might lead to different conditions, with and without heart failure. The left ventricle contractility was reduced in both groups. However, in the right ventricle contractility was reduced only in animals presenting heart failure. Results suggest the existence different remodeling mechanisms in the right ventricle after infarction in rats with same scar size depending on the presence or absence of heart failure.
Efeitos do sulfato de magnésio intracerebroventricular nas crises convulsivas induzidas pelo pentilenotetrazol em ratos
(Universidade Federal do Espírito Santo, 2006-04-28) Oliveira, Luziene Dalmaschio Biasutti de; Futuro Neto, Henrique de Azevedo; Nakamura-Palacios, Ester Miyuki; Padula, Niura Aparecida de Moura Ribeiro; Silva, Nyam Florencio da
Almost all of antiepileptic drugs currently in use act through an influence in gabaergic neurotransmission or by means of ion channels mechanisms. There are, however, only few agents acting at glutamatergic neurotransmission. The magnesium sulfate (MgSO4) has been used for many years in the prevention of seizures in eclampsia, a specific disease of pregnancy manifested by hypertension, proteinuria and seizures or even coma. This compound probably acts through a non-competitive antagonism of Mg2+ at NMDA (N-Methyl-D-aspartate) receptors. The present study examined the effects of MgSO4 administered intracerebroventricularly (icv) at different doses (32, 100 and 320 µg) on different types of seizures induced by pentylenotetrazole (PTZ) administered intraperitoneally in rats. Behavioral responses after PTZ administration were observed and registered by two experimenters. A simultaneous brain electrical activity was measured through an adapted electroencephalographic apparatus connected to electrodes implanted bilaterally in posterior parietal-temporal region. This combined procedures allowed the characterization of different types of seizures induced by PTZ in rats such as myoclonic, tonic, clonic and tonic-clonic generalized seizures and also partial complex seizures with or without following generalization. MgSO4 icv at a dose of 100 µg increased the latency for the first seizure of any king and also reduced the total period in which animals presented seizures during the experiment as compared to control treatment (saline followed by PTZ). This dose of MgSO4 also increased the latency for the first myoclonic jerk and reduced the frequency of this type of seizure, but at nonstatistical manner. The smallest dose of MgSO4 (32 µg) increased significantly the latency for the first partial complex seizure as compared to control treatment. However, the major dose (320 µg) of MgSO4 showed no effect or it was even harmful for the most parameters observed in this study for PTZ-induced seizures. These results suggested that the magnesium sulfate can be of a clinical importance as an adjuvant agent in the treatment and prevention of epilepsy depending on its dose.
Estudo etnofarmacológico das plantas medicinais utilizadas pela população com hipertensão arterial sistêmica da unidade de saúde de andorinhas no município de Vitória - Es
(Universidade Federal do Espírito Santo, 2006-10-31) Carmo, Rodrigo Alves do; Mauad, Hélder; Zandonade, Eliana; Vieira, Fernando Luiz Herkenhoff
Introduction: The modern medicine is well developed in most of the world. However, most part of population in developing countries uses medicinal plants (MP) for treatment of several diseases, as the Systemic Arterial Hypertension (SAH), which is a serious problem of public health. The objective of this study was to do a detailed ethnofarmacologic analyses regarding MP used by the population bearered of SAH at Andorinhas Unit Health, Vitória-ES. Material and Methods: There were applied 625 ethnofarmacologics questionnaires, to identify the interviewees’ profile and the MP used separately or associated to medicines, as well as their use. At the end of the interview, antropometrics values (weigh and height) and blood pressure (BP) values were measured. After determinating BP values, the individuals who assumed been SAH bearers were classified according to the IV Brazilian Guidelines of Arterial Hypertension. It was also requested, a sample of plants used for future taxonomic identification of the species. Results: Most of the population was female (72%), and used more MP (58%) that the men (38%). 39% of the individuals were mestizo, 56,4% didn’t finish primary school, 30% had family’s salary up to 1 minimum wage (MW) and 38% had salary between 2 and 3 MW. People with salaries above 5 MW use less MP than those with salaries up to 1 MW, between 2 and 3 MW and between 3 and 5 MW. Most part of population was between 50 and 70 years old, whose medium age was of 59,61±12,72 years old. Most part of individuals that use MP are 50 and 79 years old. The most used MP by the individuals, in all levels of pressure were: Melissa officinalis (lemon balm), Sechium edule (chayote), Averrhoa carambola (star fruit), Rosmarinus officinalis (rosemary), Bauhinia aff. candicans (cow paw) and xvii Cymbopogon citratus (lemon grass), among others. Conclusions: Most of the individuals of the analysed population presents tensional levels out of the normality strip. Individuals of all tensional levels use MP as a SAH treatment form. MP are used separately or associated to medicines by individuals non-controlled BP, as well as, for those that possess the BP at normal limits
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.
Efeitos imediatos do ortostatismo sobre o tempo e amplitude de reflexão da onda de pulso carotídeo e radial
(Universidade Federal do Espírito Santo, 2007-03-28) Magalhães, Pedro; Cunha, Roberto de Sá; Ferreira, Albano Vicente Lopes; Vassallo, Dalton Valentim
Background: Decreased arterial distensibility associated with orthostatism is known in humans. However, changing in the pulse pressure amplitude and in the time to reflection are not clearly described in healthier young evaluated during tilt test. We tested the hypotesis that orthostatism could lead to early pulse reflection and increase augmentation index in the carotid and in the radial arteries. Methodology: Were studied 32 healthy young male, aged 18 to 38 (mean 25 ± 5 years old). Subjects with history of cardiovascular desease, orthostatic intolerance or in current vasoactive drug therapy were excluded. Carotid and radial augmentaion index was calculated from pressure waveforms recorded manually using tonometry method in supine and 2 minutes after tilt at 70o . Simultaneously, brachial blood pressure was assessed using oscilometric method, so, the carotid blood pressure was estimated from carotid waveforms. Heart rate was calculated from R-R intervals of the electrocardiogram registrated continuously. Differences between means was tested by pared t test. Pearson coefficient (r) was determined to evaluate correlation. Regression (linear or multiple as necessary), and covariance analysis were performed. To test the influence of other variables on the means, covariance analysis was performed and P ≤ 0,05 level was considered for all significance tests. Results: Carotid augmentation index increased significantly (–35,39 ± 12,24% vs –27,75 ± 14,18%, P = 0,002), so, the radial augmentation index increased (84,65 ± 6,54% vs 88,10 ± 4,92%, P = 0,004). The time to reflection (TR) decreased significantly (234 ± 23 ms vs 188 ± 21 ms P = 0,0001). Negative correlation was observed between delta carotid augmentation index and delta pulse pressure carotid (r2 = 0,142, P = 0,026) Orthostatic changing in the carotid systolic blood pressure was not significant (96,02 ± 8,41 mmHg vs 94,71 ± 11,58 mmHg, P = 0,53). So, the same was observed to the rate of pulse pressure amplification (36,21± 18,42% vs 34,00 ± 25,75%, P = 0,681). Conclusions: Upright position during tilt test decreased the time to the pulse wave reflection and increased the carotid and radial augmentation index. Besides, the carotid systolic blood pressure and the rate of pulse pressure amplification were attenuated. These results suggest the role of carotid wave reflection to participate in the orthostatic tolerance mechanisms and human bipedalism adaptation. This approach could have implication on the understanding cardiovascular aging, hypertension and syncope associated with arterial stffness
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
Atividade funcional da Na+K+-ATPase sensível à ouabaína em aorta de ratas com e sem sinais de insuficiência cardíaca após infarto do miorcárdio
(Universidade Federal do Espírito Santo, 2007-06-22) Dias, Fernanda Moura Vargas; Rossoni, Luciana Venturini; Stefanon, Ivanita; Vassallo, Dalton Valentim
The identification of two distinct experimental groups (Icc – with, and Inf - without signals of heart failure (HF) folowing myocardial infarction in rats, presenting the same infarct area (IA), could explain, at least in part, the contradictory cardiovascular results in experimental models of HF. Recent research demonstrates the function of the Na+K + -ATPase in the vascular homostasis in the control of tonus. The activity of the Na+K + -ATPase is influenced by vasoativos factors endothelium-derivatives, cardiac glycosides, hormones, ionic concentration and shear stress, frequently altered after INF and HF. The objective of this research was to study the ouabain-sensitive Na+K + -ATPase functional activity in aortic rings of INF rats, with same IA, presenting or not signals of ICC. Female Wistar rats (220 ± 8 g), were distributed in: Sham (n= 13), Infarct without signals of ICC (Inf N = 11) and Infarct with signals of HF (Icc n= 7). MI was surgically induced by occluding left coronary artery. After 30 days the rats were anaesthetized, and the aortic rings was superfused with Krebs solution gasified with 95% O2 - 5% CO2 mixture to study rings with intact endothelium (E+), denuded endothelium (E -) and with L-NAME. The ouabain-sensitive Na+K + -ATPase functional activity was analized using the potassium relaxation technique. No differences was observed in IA (Inf: 30,2 ± 1,6; Icc: 35,6 ± 2,8), body weight (Sham: 236 ± 4 g; Inf: 236 ± 5 g; Icc: 235 ± 5 g) and VE/PC (Sham: 2,12 ± 0,05; Inf: 2,24 ± 0,06; Icc: 2,21 ± 0,07). However, the signals of HF appeared only in the Icc groups VD/PC (Sham: 0,6 ± 0,02; Inf: 0,6 ± 0,03; Icc: 1,4 ± 0,1* P<0.05) and PP/PC (Sham: 5,7 ± 0,3; Inf: 6,1 ± 0,3; Icc: 13,6 ± 1,0* P<0.05). The main results of this study are that in the Inf animals the KCl-induced relaxation was diminished and the endotelial modulation of this relaxation, for nitric oxide, was present. However, the capacity of the OUA to inhibit the Na+K + -ATPase was increased in these animals and it did not present endotelial modulation as seen in the groups Sham and Icc. These results demonstrate that OUA-dependent NO release is absent in the Inf group, but preserved in the Icc. Therefore, the results demonstrate for the first time in literature the participation of the Na+K + -ATPase in the changes of vascular reactivity following myocardial infarction in female rats. Moreover there are differences in the mechanisms involved in the aortic reactivity following myocardial infarction in female rats with same IA, presenting or not signals of HF.
Efeitos cardiovasculares e renais promovidos pelo tratamento crônico com tamoxifeno em ratas ooforectomizadas, normotensas e espontanemente hipertensas
(Universidade Federal do Espírito Santo, 2007-08-22) Sipolatti, Walckiria Garcia Romero; Abreu, Glaucia Rodrigues de; Amorim, Maria Helena Costa; Gouvea, Sonia Alves
Cardiovascular diseases and breast cancer strike a large proportion of Brazilian women, especially at the post-menopause period. As both conditions afflict the same age group with corresponding health risks, there is a need for testing women with breast cancer for potential heart problems. Although estrogen is associated with a decrease in cardiovascular risks, it has also been identified as a contributor to the development of breast cancer in women. Tamoxifen was approved in 1998 for the treatment of breast cancer and is used for women at high risk of contralateral breast cancer. The drug acts as an estrogen receptor agonist in some tissues and as an antagonist in others and is part of a class of medication known as SERMs - selective estrogen receptor modulators. This study aimed at evaluating the effects of tamoxifen on body metabolism, renal function, cardiovascular system and hepatic function. The experiment was done with 36 female rats, surgically castrated, dived into 4 groups (n=9): Wistar control (WC), Wistar treated with tamoxifen (WT); spontaneous hypertensive rats – SHR control (SC), SHR treated with tamoxifen (ST). Rats were kept in metabolic cages for 90 days with free access to water and chow. Tamoxifen was administered at a concentration of 0.1 mg/day/100 g the rats’ body weight. Ingestion of water, dieresis and chow consumption were monitored and recorded on a daily basis, while body weight was weekly checked to adjust the drug regimen. Following treatment, rats were anesthetized with ketamin, (10 mg/kg) and xylozine (50 mg/kg) and catheterization of both the femoral artery and carotid artery (with the cannula until to the left ventricle) was performed an 24 hours later, with rats awake, mean arterial pressure (MAP) and myocardial contractility index were measured in maximum developed pressure during the isovolumetric phase (dP/dtmax). Our findings suggest that the body weight gain in tamoxifen-treated rats was significantly lower than in the control group, despite the fact that there was no difference in chow consumption. There was also no difference in the relation between liquid intake and urinary excretion in the groups. As to renal weight, the ST group showed a marked loss. Serum levels of sodium, potassium and creatinine remained unaltered after treatment. Histopathological analysis of the renal blade revealed no differences between hypertensive and normotensive groups. Heart rate (HR) and MAP decreased significantly in the ST group, followed by a decrease in dP/dtmax. The humid weight of the left ventricle was also significantly lower in the ST group as compared to the control group, but there were no alterations in the Wistar group. Treatment with tamofixen increased HDL cholesterol in the ST group when compared to the SC group, but again there were no alterations in the Wistar group. LDL cholesterol and total cholesterol were significantly reduced in the animals treated, both in the normotensive and the hypertensive. High levels of glutamic-pyruvic transaminase and liver humid weight were found in the WT and the ST groups, when compared to their control groups. The findings in our study show that tamoxifentreated female rats presented a lower risk of cardiovascular diseases for the duration of the treatment. Further research might confirm the cardiovascular and renal benefits of tamoxifen therapy in the treatment of breast cancer.
O antagonista seletivo dopaminérgico D² sulpirida, no córtex pré-frontal medial reduz os prejuízos do etanol sobre a memória operacional de ratos
(Universidade Federal do Espírito Santo, 2007-08-31) Benevides, Marcelo Campos de Almeida; Palacios, Ester Miyuki Nakamura; Pires, Jose Guilherme Pinheiro; Ribeiro, Sidarta Tollendal Gomes
The prefrontal córtex (PFC) has been considered as the anatomical site for working memory processing. Its medial portion (mPFC) is part of a brain reward circuitry, essentially mediated by the dopaminergic mesocorticolimbic pathway. The present study examined the involvement of dopaminergic D2 receptors in the mPFC, by means of a selective antagonist of D2 receptors, sulpiride, in the disruptive effects of ethanol (ETOH) on long-term spatial working memory measured by 1-h delayed task performance in an 8-arm radial maze. Male Wistar rats (n=26, 210-270g, ≅ 3 months of age), previously trained in the 8-arm radial maze and with bilateral cannulae implanted in the mPFC (B: + 2.5 mm A, +/- 1 mm L, 2.0 mm V), received intracortical (IC) administration of sulpiride in two different experiments: in the first experiment, 11 animals received IC administration of different doses of sulpiride (0.32, 1.0 or 3.2 µg) or chloride acid 0,05M (HCl) 10 minutes before IC administration of saline (SAL) or ETOH 100 µg. Five minutes after the second administration, animals were submitted to the 1-h delayed task in the radial maze. In the second experiment, 22 animals received IC infusions of sulpiride 1 µg or HCl 0,05 M directly in the mPFC once a day for 4 consecutive days. After the last (4th) administration, animals received acute IC administration of SAL or ETOH 100 µg in the 3rd day, followed by 4-days intervals (days 7, 11 and 15), and tested in 1-h delayed task in the radial maze, after a 5 minutes interval. ETOH IC with previous administration of HCl or sulpiride (3.2 µg) IC yielded significantly larger (p < 0.01) number of errors as compared to the combination of HCl and SAL. Animals treated with lower doses of sulpiride (0.32 µg or 1 µg) combined with ETOH showed significantly (p < 0.01 and p < 0.05, respectively) smaller number of errors as compared to the combination of HCl and ETOH (100 µg) and of sulpiride (3.2 µg) and ETOH (100 µg) in the 1-h post-delay performance. Previous repeated administration of sulpiride into the mPFC did not affect substantially the disruptive effects of ETOH on spatial working memory over the 15 days period, but it significantly reduced the ETOH disruptive effect after the latency of 15 days, suggesting that reduced dopaminergic D2 receptors in the mPFC could change the effects of ETOH in the mPFC. Taken all together, these results suggest the involvement of the dopaminergic system, more specifically the D2 dopaminergic receptors, in ethanol effects on spatial working memory in the mPFC.
Atenuação do reflexo Bezold-Jarisch após tratamento crônico com doses suprafisiológicas de decanoato de nandrolona em ratos sedentários
(Universidade Federal do Espírito Santo, 2007-09-27) Medeiros, Ana Raquel Santos de; Bissoli, Nazaré Souza; Stefanon, Ivanita; Andrade, Tadeu Uggere
While there clinical applications of anabolic-androgenic steroids (AAS), the misuse of AAS is widespread and is not limited to competitive athletes but the majority of AAS abusers are noncompetitive recreational bodybuilders and even nonathletes. Objective: we investigated the influence of treatment with an AAS on the BezoldJarisch reflex (BJR) control of heart rate (HR) and whether this treatment induced cardiac hypertrophy and anabolic effects in rats. Methods: male rats were treated with nandrolone decanoate (ND; 10 mg.Kg-1 body weight/8 wks; DECA) or vehicle control (CON). After 8 wks, the BJR was evaluated by bradicardia responses elicited by serotonin administration (2-32 µg.Kg-1). Mean arterial pressure (MAP) was assessed and cardiac hypertrophy was determined by the left or right ventricle weight/body weight (LVW/BW; RVW/BW; respectively). The measurement of the total body protein content of the animals was performed. Results: ND treatment determined an elevation of the MAP of DECA animals compared with CON group (CON = 99 ± 1; DECA = 109 ± 2 mmHg; p<0.01). There was no change in the mean basal HR of DECA animals (CON = 356 ± 13; DECA = 367 ± 11 bpm). The LVW/BW and RVW/BW ratios indicated significant hypertrophy of the LV and RV in DECA animals (CON = 1.86 ± 0.04, DECA = 2.17 ± 0.04, p<0.01; CON = 0.42 ± 0.02, DECA = 0.53 ± 0.03 mg.g-1, p<0.05; respectively). Total body protein content was enhanced in DECA group compared with CON rats (CON=18.2 ± 1%, DECA = 28.0 ± 1%; p<0.01). In the last two doses of serotonin the BJR control of HR was significantly blunted in DECA rats compared with CON group (CON = -61 ± 4% and -76 ± 3%; DECA = -47 ± 4% and -66 ± 3%; p<0.01 and p<0.05, respectively). Conclusions: We conclude that 8-wks ND treatment induces an anabolic effect, cardiac hypertrophy and an elevation of the MAP in DECA rats. The treatment 15 reduces the sensitivity of the BJR control of bradicardia, what could be explained by the presence of a cardiac hypertrophy and/or an elevated MAP in DECA animals.
Participação dos receptores nicotínicos na neurotransmissão da resposta cárdio-vagal do barorreflexo e do reflexo Bezold-Jarisch no núcleo ambíguo de ratos anestesiados
(Universidade Federal do Espírito Santo, 2007-10-11) Pedrosa, Diego França; Mauad, Hélder; Amaral, Fabian Tadeu do; Sampaio, Karla Nívea
Immunohistochemical studies have demonstrated that the nucleus ambiguus (NA) plays a predominant role in the cardio-vagal control. Using the kynurenic acid blockade, previous studies demonstrated that the excitatory aminoacids receptors of NA neurons have an important role in mediating the negative chronotropic response of baroreflex (BRF) and Bezold Jarisch reflex (BJR) in anesthetized rats. However, there are other aspects that need a better understanding, as the role of nicotinic cholinergic receptors in mediating the participation of the reflex bradicardic response, as well as, the possible influence of these receptors on L-glutamate-induced responses in the NA. The goal of the present study was to evaluate the nicotinic cholinergic receptors participation in modulating the cardiovascular responses induced by BRF and BJR activation and to study a possible interaction between the glutamatergic and nicotinic cholinergic neurotransmission in the NA. Male Wistar rats were used. The animals were anesthetized with urethane, paralyzed with succinylcholine and artificially ventilated. The femoral artery and vein were cannulated for cardiovascular recording and for drug administration, respectively. The sympathetic cardiac activity was blocked with atenolol, a β-adrenoceptor antagonist. Microinjections into the NA were performed at the level of the óbex, following the coordinates based in Paxinos and Watson (1998), ±1.7 mm lateral to the midline and -1.4/-1.7mm ventral to the dorsal surface of the óbex. The drugs used in this study were: L-Glu (5 nmol/50 nL), nicotine (0,5; 1; 5 e 10 mM), αbungarotoxin (1 µM), DH-β-E (100 µM) and control solutions (saline, NaCl 0,9%). The BRF was evoked with a continuous phenylephrine infusion (50 µg/mL/min), and the BJR with an intravenous injection of phenylbiguanide (10 µg/Kg). Our results demonstrated that L-Glu microinjected into the NA produced minimum hypotension and consistent bradycardia. The nicotine microinjections produced significant bradicardic and discrete pressure responses at 1 and 5 mM dosis. At 10 mM dosis, neither bradicardic or pressure responses were no longer observed. The DH-β-E unilateral microinjection at NA did not result in significant alterations in L-Glu induced responses, however, the α-bungarotoxin unilateral microinjection attenuated the LGlu and nicotine-induced bradicardic responses. Regarding the cardiovascular reflexes, the blockade with α-bungarotoxin attenuated significantly the BRF, while only the BJR bradicardic response was attenuated. The present results confirm that the NA plays an important role in modulating cardiovascular responses. They also suggest that the α7 nicotinic cholinergic receptors subunits, at Óbex level, participate of BRF and BJR cardio-vagal reflex responses in anesthetized rats. Regarding the glutamatergic neurotransmission, our results showed that the nicotinic cholinergic receptors intervene at glutamatergic cardiovascular responses. However, additional studies are needed to elucidate this interaction occurs at L-glutamate releasing from NTS projections or directly at the excitatory aminoacid receptors in the NA
Evolução da periodontite experimental em ratos na ausência e presença de hipertensão arterial renovascular
(Universidade Federal do Espírito Santo, 2007-11-01) Silva, Lídia Maria Rosa da; Velloso, Tânia Regina Grão; Meyrelles, Silvana dos Santos; Cabral, Antonio de Melo
Periodontal disease is a chronic and multifatorial inflammatory disease, that results from a unbalance between the host and the microorganisms of dental biofilm and can lead to tooth loss. Although there are evidences that periodontal disease may influence the general health and the suceptibility to determinated systemic diseases, there are few investigations regarding the relationships between periodontitis and arterial hypertension. Therefore, the goal of this study was to evaluate histological changes induced by renovascular hypertension in rats with periodontal disease. Male Wistar rats (5 week-old, 150-170 g) were separated in two groups: Hypertensive (n=6) and SHAM (n=5). The animals were anesthetized, submitted to laparotomy and only the hypertensive group received a silver clip in the left renal artery (2K1C). Fourteen days after this procedure, the animals were submitted to experimental periodontitis induction through the subgengival ligature at first left inferior molar. The non-ligated contralateral molar was considered as control situation. Once again, fourteen days after the periodontitis induction, the MAP (109±1,4mmHg SHAM vs 178±5mmHg hypertensive) and HR (351±4bpm SHAM vs 370±12bpm hypertensive) hemodynamic measurements were performed in the conscious animals. The animals were sacrificied and the jaw was removed to histological processing. The parameters used to evaluate the periodontitis were: PMNs, the number of blood vessels and alveolar bone loss in the ligated and control molar at distal interproximal region. The results showed that there were a significant raise in PNMs and number of blood vessels at the periodontitis side when compared to control side in SHAM animals (2,2±0,3 vs. 14,6±2,2 and 4,6±0,8 vs. 13,1±1,7 respectively) and hypertensive animals (2,3±0,3 vs. 15±0,9 and 4,5±0,84 vs. 13,1±1,8 respectively). Although there are significant changes between the ligated and non ligated molar in each group, there were no differences in bone loss between the ligated molar of SHAM (0,74±0,07mm) and hypertensive (0,87±0,10mm) animals. Based on these data, we can conclude that in rats, the renovascular hypertension did not agravatted the periodontal disease.
Função ventricular direita de corações isolados de ratos com e sem sinais de insuficiência cardíaca oito semanas após infarto agudo do miocárdio
(Universidade Federal do Espírito Santo, 2007-11-13) Moura, Viviane Guimarães Carvalho de; Stefanon, Ivanita; Vassallo, Dalton Valentim; Araújo Sobrinho, Aloir Queiroz de
Recent studies performed in our laboratory the demonstrated that rats submitted to myocardial infarction (MI), presenting same infarct area, may develop or not heart failure (HF). Moreover, the study of right ventricle (RV) isolated strips showed that contractility is preserved following MI in rats without HF signals with similar infarct area. However, it is unknown if such response occurs in the isolated heart preparation. In Langendorff perfused hearts is possible to evaluate the contractile performance by using inotropic interventions independent of any extrinsic mechanism of contractility control. Thus, the aim of the present study was to investigate the RV performance of hearts under isovolumetric contraction of rats with and without HF signs after 8 weeks of MI. Male Wistar rats were divided in three groups: control (SHAM, n= 11); infarction without HF signs (INF, n= 11) and infarction with HF signs (HF, n= 11). The in vivo results showed improvement of RV function in the HF group (RVSP= 48 ± 2.2* mmHg; RVEDP= 4.5 ± 0.8*; mmHg; dP/dt+= 2046 ± 226* mmHg/s; dP/dt- =1807 ± 84* mmHg/s; *p<0.05). In the INF group the RV function remained unaltered (RVSP= 31 ± 2.6 mmHg; VEDP= 1.2 ± 0.4 mmHg; dP/dt+= 1192 ± 165 mmHg/s; dP/dt-= 1239 ± 156 mmHg/s). The HF group included the animals that presented increase in LVEDP (HF= 13.0 ± 1.8* vs. INF=2.6 ± 0.5; SHAM= 3.2 ± 0.4 mmHg; *p<0.05), RV hypertrophy and increase on wet weight of lungs. The infarct area was similar between groups (INF= 27.6 ± 1.2 e HF= 29.2 ± 0.8%). Nevertheless, in vitro results were different of those obtained in vivo. The heterometric mechanism of contractility regulation, obtained by stretch-tension curve (DP= 0 - 30 mmHg, and the homeometric mechanism, obtained by [Ca+2]e response concentration curve (0.62 mM – 3.75 mM) and isoproterenol administration (5x10-5 M), were impaired in the RV HF animals. The main results presented here demonstrated that infarcted rats with HF signs presented better RV performance in vivo than in vitro. These findings suggest that, in the HF animals, the neurohumoral mechanisms are important to maintain the heart function. Second, INF rats presenting the same infarct area, showed a normal RV function in vivo, wich suggest that, in these animals, the HF are not dependent on the infarct size.

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