The Effect Of Connexin 43 In Myocardial Protection Of Ischemic Preconditioning

Objective To study the effect and status of connexin 43 in myocardial protection of ischemic preconditioning. To investigate whether sufentanil could relieve myocardial ischemic-reperfusion injury in rats. To investigate the mechanism of mitochondrial ATP sensitive potassium channel in ischemic preconditioning. Methods Made ischemia-reperfusion models by ligating the left anterior descending artery. Seventy two Sprague-Dawley rats were randomly divided into six groups (n=8): sham operated group (Sham group), ischemia-reperfusion group (IR group), ischemic preconditioning group (IPC group), sufentanil preconditioning (SPC group), 5-hydroxydecanoate acid and ischemic preconditioning group (5-HD+IPC group) and 5-hydroxydecanoate acid and sufentanil preconditioning group (5-HD+SPC group). The arrhythmia score and myocardial infarct size of six rats in each group were measured, and the expression of connexin 43 of other rats was detected by immunohistochemistry (SP method) and RT-PCR . Results In sham group, myocardial fibers arranged regularly, and myocardial cells morphology was normal. Regional myocardial necrosis, pyknosis and karyorrhexis could be seen in IR group, 5-HD+IPC group and 5-HD+SPC group. And there were slight myocardial injury in IPC group and SPC group. Compared with sham group, there were notably significant differences in the arrhythmia score and the expression of connexin 43 of IR group, 5-HD+IPC group and 5-HD+SPC group (P<0.01). But there were not significant differences in the arrhythmia score and the expression of connexin 43 of IPC group and SPC group compare to sham group (P>0.05). And there was not significant differences between IPC group and SPC group (P>0.05). Compared with IR group, there were notably significant differences in the arrhythmia score and the expression of connexin 43 of IPC group and SPC group (P<0.01). But there were not significant differences in the arrhythmia score and the expression of connexin 43 of 5-HD+IPC group and 5-HD+SPC group compare to IR group (P>0.05). There was notably significant differences in the arrhythmia score and the expression of connexin 43 of 5-HD+IPC group compare to IPC group (P<0.01). And there was also significant differences in the arrhythmia score and the expression of connexin 43 of 5-HD+SPC group compare to SPC group (P<0.01). Conclusions (1) Ischemic preconditioning might play an important role in myocardial protection by activating mitochondrial ATP sensitive potassium channel and preserving connexin43 posphorylation. Connexin43 might play an important role in ischemic preconditioning. (2) 5-hydroxydecanoate acid might abolish the effect of ischemic preconditioning in myocardial protection which indicate that mitochondrial ATP sensitive potassium channel might participate in the mechanism of myocardial protection. (3) Sufentanil preconditioning might reduce the incidence rate of arrhythmia and myocardial injury which might act as ischemic preconditioning in myocardial protection.