Abstract: AIM: To determine whether isosorbide dinitrate (ISDN) could induce late ischemic preconditioning in rats.METHODS: SD rats were divided into oral normal saline (control group), oral ISDN (0.2mg·kg^-1, ISDN group), SHAM grouP;oral normal saline combined with ischemia and reperfusion(I/R) (I/R control group), ISDN plus I/R group, ISDN plus Gly plus I/R group, Gly plus I/R control grouPand late ischemic preconditioning grouP(3 cycles of 5-min coronary occlusion 5-min reperfusion, LPC group).24 h later,rats, like other groups with I/R, were underwent a 40 min coronary occlusion followed by 1.5 h of reperfusion.RESULTS: Myocardial infarct size and the levels of creatine kinase (CK) in serum were significantly reduced after pretreated with ISDN +I/R versus I R control group(P<0.05), so was lactate dehydrogenase (LDH) (P<0.01).Nitric oxide and Mn-superoxide dismutase in heart tissue were significantly elevated, while MDA was significantly reduced (P<0.05).The level of induced nitric oxide synthetase (iNOS) in heart tissue was significantly elevated in the ISDN grouPcompared with controls(P<0.01).CONCLUSION: ISDN induces delayed cardioprotection against myocardial infarction similar to that afforded by the late phase of ischemic PC, possibly by up-regulating NO and iNOS, and strengthening antioxidant mechanism.

Key words: isosorbide dinitrate, ischemic preconditioning, induced nitric oxide synthetase, Mn-superoxide dismutase, rat