Abstract: Objective To explore the mechanism of protecting effect of Nicorandil on isolated heart of rats in cold preservation solution. Methods A total of 24 SD male rats were randomly divided into a control group and nicorandil group, in which the rats were injected intraperitioneally with distilled water or nicorandil 0.1 mg·kg^-1·d^-1 for 9 days respectively. After the last injection, every isolated heart was stored in 4 ℃ St-Thomas solution. The myocardial tissue was taken from the anterior wall of the left ventricle at 2, 4, 6, 8, 10, 12, 16, 20 and 24 hours respectively. The contents of MDA and the changes of ultrastructure of myocardial tissue were observed. The protein expressions of HSP70 were examined by using immunohistochemical staining and Western blotting. Results The ultrastructure of myocardial tissue changed more significantly in the nicorandil group. MDA concentrations were reduced significantly in the nicorandil group compared with those of the control group(P<0.05). With the time prolonged, the expression of HSP70 increased gradually and dropped later as parabola-related curves in nicorandil group compared with the basement expression of HSP70 in control group respectively. The peak expression of HSP70 was seen at 6 hours and significantly decreased at 24 hours in nicorandil group. The correlation between MDA and HSP70 are significant(P<0.05). Conclusion Nicorandil preconditioning may have a protective effect in the isolated rat heart by the induction of the early endogenous HSP70 expression.

Key words: nicorandil, HSP70, pharmacological precondition, isolated heart