Protective Effect Of Nitric Oxideon Myocardialcells By Anoxia/reoxygenation In Rat Via Activation Of K_ATP Channels

Research Background and AimIschemia/reperfusion (I/R) injury is refered to the phenomena that the cardiac damage was deeply aggravated through some certain time ischemia followed by reperfusion. Long time ago, cardioprotective effect is the stess in the field of cardiovasology, Ischemic preconditioning(IPC) has been proved to be the most effective endogenous protective mechanism of protecting the heart against ischemia/reperfusion(I/R) injury up to now. However, as an endogenous protective mechanism, IPC could not be used directly as a clinical therapeutic method, which limited its applications. Pharmacological preconditioning(PC) has more clinical application, Therefore, pharmacological agents capable of imitating IPC and protecting the heart from infarction have been the subjects for intensive research. The protection of IPC has contained several agents, but compared the agents, we can see NO has its unique advantage. NO donor drugs have been widely applied in clinc and they have been proved to be safe, although the effect of NO in cardiovascular diease to protect or to posion is still disputed. Many studies inclined to the profective effect. At present, there are many studies on the signal-transmitting of IPC, but the way of signal-transmitting is verycomplicated. ATP-sensitive potassium channel has increasingly accepted notice as the last way. Current study indicated that the open of KATP has cardioprotective effect.Tt has been proved on the cultured rat cardiomyocyte and human atrial cardiomyocytes.In this studuy, NO donor mimicked IPC to deeply study the effect of NO on myocardial cells by anoxia/reoxygenation, and the Protective effect via activation of KATP channels.MethodsNeonatal SD rat cardiomyocytes were isolated and cultured in vitro, with which to establish models of myocardial hypoxia-reoxygenation, SNAP and Gly were adopted as intervening factors respectively and different groups were randomized. Fluoromicroscope was used for morphology; The oxidative level was reflected by examining quantity of malondialdehyde (MDA) in myocardium; Intracellular calcium concentration was detected by laser scanning confocal microsopy. The extent of myocardial necrosis was reflected by release of myocardial enzymes and the cell livability. Data in the results was statistically analized with SPSS software.Results and Conclusion1. In short time, anoxia/reoxygenation induced the injury of neonatal rat cardiomyocytes.mianly in the activity of CK, LDH and the rate of cell viability.2. The level of MDA has increased after noxia/reoxygenation, 0 1mmol/L and lmmol/1 SNAP group significantly attenuated the levels of CK,LDH and MDA. 2mmol/LSNAP group caused great increases of levels. NO can decreased the level of MDA, so it indicated NO inhibiting lipid peroxidation and attenuating the oxygen free radicals mediating damage to the myocardium. And its effect is concentration dependent.3. Anoxia/reoxygenation injury induced the intracellular Ca2+ overload. 0.1mmol/L SNAP group and Immol/L SNAP group significantly attenuated the change (P<0.01vs B) , and 2mmol/L SNAP group deeply increase the level of intracellular Calcium. NO has protective effects on anoxia/reoxygenation injury of neonatal rat cardiomyocytes by attenuating the overload of intracellular calcium, and its effect is concentration dependent.4. Glybenclamide group partly abolished the protective effects of NO. It indicated activation of KATP channels mediated protective effect of NO in anoxia/reoxygenation injury of neonatal rat cardiomyocyte.