Effect of endogenous nitric oxide on cardiac ischemic preconditioning in rat

Introduction: Ischemic Preconditioning (IPC) is the phenomen that happens on the heart by one or several short periods of ischemia followed by reperfusion that improve the postischemic recovery of mechanical function. Ischemic preconditioning (IPC) may protect the heart from ischemia reperfusion injury by nitric oxide formation. This study investigated the effect of ischemic preconditioning on heart and the relationship between nitric oxide. Methods: 28 male Sprague dawley rats (200-250 g) in Tehran University of Medical Sciences were used. Rats were anesthetized and hearts were rapidly isolated and perfused in the Langendorff mode at a constant perfusion pressure and temperature of 37 ̊C. hearts were divided to 4 groups. Control group was perfused 170 minutes with buffer solution. ischemic reperfusion (IR) group was subjected to 30 minutes ischemia. (Ischemic preconditioning) IPC group was elicited by 5 min ischemia followed 5 min reperfusion before IR and L-NAME + IPC group, L-NAME (0.1mM) was added into the perfusion solution. Heart rate (HR), left ventricular development (LVDP), RPP (LVDP × HR), infarct size and coronary flow (CF) were measured. ANOVA tests( with TUKEY post test if p<0.05) were used for statistical analyses. Results: IPC improve the postischemic recovery and reduced postischemic ventricular dysfunction in heart and reduction of infarction size. No significant differences were observed between IPC and IPC + L-NAME groups. Conclusion: L-NAME did not affect postischemic recovery of IPC so in the isolated heart NO isn't involved in the cardioprotective effect of IPC.