Role of cadiocyte connexin 43 in mito-KATp channel mediated cardioprotection against ischemia-reperfusion injury induced by sevoflurane preconditioning in isolated rat hearts

Objective To evaluate the role of cadiocyte connexin 43 (Cx43) in mito-KATP channel mediated cardioprotection against ischemia-reperfusion(I/R) injury induced by sevoflurane preconditioning in isolated rat hearts.Methods Forty hearts from male adult SD rats weghing 200-250 g were excised and perfused in a Langendorff apparatus with K-H solution with 95 ％ O2-5 ％ CO2 at 36.5-37.5 ℃.Their hearts were randomly divided into 5 groups (n =8 each): control group (group C),group I/R,sevoflurane preconditioning group (group S),sevoflurane preconditioning + 5-HD group (group SH) and 5-HD group (group H).Myocardial I/R was induced by occlusion of the anterior descending branch of left coronary artery (LAD) for 30 min followed by 120 min reperfusion.After 10 min of equilibration,group C received continuous perfusion and LAD was exposed but not occluded.Group I/R received continuous perfusion for 30 min and LAD was occluded.In group S,SH and H,3％ sevoflurane,3 ％ sevoflurane mixed with 100μmmol/L 5-HD and 100 tmmol/L 5-HD was added into K-H solution to perfuse for 15 min respectively.After that,the hearts were washed by K-H solution for 15 min.HR,left ventricular systolic pressure ( LVSP),left ventricular diastolic pressure (LVDP) and ± dp/dtmax were recorded before administration (T0),immediately after administration (T1),immediately before ischemia ( T2 ),at 30 min of ischemia (T3) and 120 min of reperfusion (T4).At the end of reperfusion,left ventricular tissue was removed for determination of myocardial infarct size and expression of Cx43 and phosphor Cx43 (p-Cx43) by immunohistochemistry and Western blot respectively.Results Compared with group C,HR,LVSP and ± dp/dtmax were significantly decreased,LVDP was increased and the expression of Cx43 and p-Cx43 were down-regulated in groups I/R,SH and H (P ＜ 0.05).Compared with group I/R,HR,LVSP and ± dp/dtmax were significantly increased,LVDP and myocardial infarct size decreased,and the expression of Cx43 and p-Cx43 up-regulated in group S ( P ＜ 0.05),no significant difference was found in groups S + H and H( P ＞ 0.05 ).Conclusion Sevoflurane preconditioning can open mito-KATP channel,promote cadiocyte Cx43 phosphorylation,attenuate I/R injury in isolated rat hearts. Key words: Connexin 43 ;  KATP channels;  Anesthetics, inhalation;  Ischemic preconditioning; Myocardial reperfusion injury