Efeitos da N-acetilcisteína no precondicionamento isquêmico: estudo em corações isolados de ratos

Abstract

Efeitos da N-acetilcisteína no precondicionamento isquêmico: estudo em corações isolados de ratosEffects of n-acetylcysteine on ischemic preconditioning. Study in isolated rat hearts Abstract Objective: The aim of this study is to assess if NAcetylcysteine (NAC) changes the Ischemic Preconditioning (IP) in isolated rat hearts using only one cycle of IP.Methods: Heart Rate (HR), Coronary Flow (CF) and Myocardial Contractility (dP/dt) were registered in 30 Wistar rat's hearts. After anesthesia the hearts were removed and perfused with Krebes-Hensleit equilibrated solution with 95% of O 2 and 5% of CO 2 according Langendorff's method. GI: Control (n=6); GII: 20 min. ischemia (n=6); GIII: IP (n=6); GIV 50 ìg/ml/min NAC before IP (n =6); GV: 100 ìg/ ml/min NAC before IP (n=6). Parameters were measured after 15 min. of stabilization (T 0) and T3, T5, T10, T15, T20, T25 and T30 min. after reperfusion. Statistical significance was considered when P<0.05.Results: There were changes on HR comparing GI with GII at T20 and T25 and comparing GI with GIII, GIV with GV at T10 and T20 (P<0.05). CF was different comparing GI with GII at T3 and T5, GI with GIV at T10 and GI with GV at T10 and T25 (P<0.05). Myocardial Contractility was similar comparing GIII with GI and GV. GIII had higher dP/dt than GIV but without statistical difference (P>0.05). dP/dt was higher in GV than GIV but with statistically significant difference only at T30.Conclusion: dP/dt was better in preconditioned hearts and was changed if using NAC in GIV. The use of NAC didn't change the effects of preconditioning on myocardial contractility in GV. Descriptors 24OLIVEIRA, DM ET AL -Effects of n-acetylcysteine on ischemic preconditioning. Study in isolated rat hearts Bras Cir Cardiovasc 2009; 24(1): 23-30 Rev INTRODUCTIONMyocardial protection during heart surgery has been the focus of basic and clinical research in the last 50 years [1]. In 1955, Lewis was the first to perform in human intracardiac surgery using hypothermia. Melrose proposed the use of cardiac arrest using an infusion of potassium in the ascending aorta. Since then, numerous tactics and techniques of myocardial protection have been developed.Murry et al.[2] described the mechanism of ischemic preconditioning (IP) by showing that short episodes of ischemia and reperfusion before a prolonged ischemic event would reduce the size of infarction and improved cardiac function. In experimental studies, this mechanism is considered the most powerful natural way of cardioprotection [3]. Studies with IP in heart surgery have shown conflicting results, but the majority confirmed that the IP is an effective adjunct in myocardial protection [3][4][5].Clinical studies in cardiology and heart surgery showed tendency to cardioprotection by using adenosine, but the effects are not as obvious as those observed in experimental researches [3,4]. Morris and Yellon [6] emphasized the existence of a threshold of stimulation, with the need of activation not only of adenosine receptors, but also of bradykinin and ...

Pantoprazol oferece proteção miocárdica semelhante ao pré-condicionamento isquêmico

“…These results associate the benefits of omeprazole with the results reported by studies addressing myocardial protection with ischemic preconditioning [8,[25][26][27][28]. The pharmacokinetics basis may be related to changes in transmembrane H + /K + gradients, the first markers of myocardial ischemia, responsible for the repolarization expressed in T-wave morphology of the electrocardiogram [29].…”

Proteção da recuperação funcional do miocárdio pelo omeprazol após isquemia-reperfusão em corações isolados de ratos

“…These results associate the benefits of omeprazole with the results reported by studies addressing myocardial protection with ischemic preconditioning [11][12][13][14][15]. The pharmacokinetics basis may GOMES, OM ET AL -Proteção da recuperação funcional do miocárdio pelo omeprazol após isquemia-reperfusão em corações isolados de ratos…”

Remote Ischemic Preconditioning and N-Acetylcysteine in Autologous Ovarian Transplantation in Rats.

“…The association of both treatments was unviable, leading to death of all five animals from R-IPC+NAC group, possibly, a collateral effect of an overdose of NAC, which has been associated in other studies with decrease in prothrombin index and anaphylactoid reactions [21]. Therefore, it has been demonstrated that NAC significantly inhibits the protective mechanism of pre-conditioning for organs such as the myocardium [22].…”