Desempenho contrátil do ventrículo direito 7 dias após infarto em ratos com e sem sinais de insuficiência cardíaca
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Data
2009-08-26
Autores
Arêas, Guilherme Peixoto Tinoco
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Universidade Federal do Espírito Santo
Resumo
Previously results from our laboratory have demonstrated a different ventricular performance in rats with same scar size (SS) depending on the presence of signals of heart failure (HF) at 30 and 60 days after myocardial infarction (MI). The aim of this study was to analyze the right ventricle (RV) contractility in an early phase (7 days) after MI. Wistar male rats (220 e 240 g) were divided in: control (SHAM), infarct (INF) and infarct with signs of HF (HF). The hearts were isolated and perfused with Krebs solution, 33oC, pH 7.35 using Langendorff technique. The RV contractility was assayed by measuring RV and the first temporal derivative of pressure (dP/dt) during length-tension curves from 0 to 30 mmHg, a single dose of angiotensin I 20 nM (ANG I), angiotensin II 20 nM (ANG II), isoproterenol (10-5 nM) and during increment of Ca2+ concentration (0.62 to 3.5 mM). The RV systolic pressure (RVSP) and the RV end diastolic pressure (RVEDP), assessed in vivo, were higher in the HF group (30.8 ± 0.8 %), whereas in the INF group, with same SS (31.6 ± 1.6 %), it remained unaltered (RVSP: SHAM=29±2.2; INF=28±2.2; HF=40±2.3*# mmHg ; PDfVD: SHAM=1.13±0,2; INF=1.33±0,3; HF=2.2±1,2*#mmHg; dP/dt+ RV: SHAM=971±191; IC=1915±210* mmHg/s, *p<0.05). The “in vivo” left ventricle pressures were different among groups (LVSP: SHAM=104±1.58; INF=92±1.17* ; HF=95±2.9* mmHg; LVEDP: SHAM=3.35±0.9; INF=3.6±0.9; HF=18±1.5* mmHg, * P<0.05). In the Langendorff perfused hearts, the RV isovolumic systolic pressure (RVISP), +dP/dt and -dP/dt in response to increment in the Ca2+ concentrations and to isoproterenol were reduced in the HF group and preserved in the INF group. The perfusion with ANG I and ANGII did not induced a inotropic response in all groups. The results demonstrated that, in vivo, the RV function is preserved in the INF group and increased in IC group. On the other hand, in the isolated heart the contractility was preserved in the INF, but it was reduced in the IC. In conclusion, it was demonstrated that 14 early after MI animals with same scar size may present or not HF. The RV contractility was preserved only in the MI animals without signals of HF