Effects of sevoflurane preconditioning on zonula occludens-1 during myocardial ischemia-reperfusion in rats in vitro

Objective To evaluate the effects of sevoflurane preconditioning on zonula occludens-1 (ZO-1) during myocardial ischemia-reperfusion (I/R) in rats in vitro.Methods Adult male Wistar rats,weighing 250-300 g,were anesthetized with intraperitoneal pentobarbital 30 mg/kg and heparinized.Their hearts were excised and perfused in a Langendorff apparatus with K-H solution saturated with 95％ O2-5％ CO2 at 37 ℃.Eighteen isolated rat hearts were randomly assigned into 3 groups (n =6 each) using a random number table:control group (group C),group I/R and sevoflurane preconditioning group (group S).At 10 min of equilibration,the hearts were perfused with K-H solution for 110 min in group C,the hearts were perfused with K-H solution for 20 min,and then subjected to 30 min of ischemia followed by 60 min of reperfusion in group I/R,and the hearts were perfused with K-H solution saturated with 3％ sevoflurane for 15 min followed by 5 min washout,and then subjected to 30 min of ischemia followed by 60 min of reperfusion in group S.At the end of equilibration,immediately before ischemia,and at 15 and 60 min of reperfusion (T1,2),HR,left ventricular end-diastolic pressure (LVEDP),left ventricular developed pressure (LVDP),+ dp/dtmax and-dp/dtmax were recorded.The development of arrhythmias was recorded during reperfusion and scored.At 60 min of reperfusion,myocardial specimens were obtained from the apex of heart for determination of the expression of ZO-1 in myocardial tissues (by Western blot) and for observation of distribution of ZO-1 and connexin43 (Cx43) (by immunofluorescence).Results Compared with group C,HR,LVDP,+ dp/dtmax and-dp/dtmax were significantly decreased and LVEDP was increased at 15 and 60 min of reperfusion,scores of arrhythmia was increased,and ZO-1 expression was down-regulated in I/R group.Compared with group I/R,HR,LVDP,+ dp/dtmax and-dp/dtmax were significantly increased and LVEDP was decreased at 15 and 60 min of reperfusion,arrhythmia was decreased,and ZO-1 expression was up-regulated in group S.ZO-1 and Cx43 were co-localized at the intercalated disk.ZO-1 was redistributed in the lateralization of the membrane and co-localized with Cx43 in group I/R.The incidence of ZO-1 lateralization was significantly decreased in group S.Conclusion The mechanism by which sevoflurane preconditioning decreases reperfusion arrhythmia is related to inhibition of down-regulation of expression and redistribution of ZO-1 and inhibition of redistribution of Cx43 in rats. Key words: Anesthetics, inhalation;  Ischemic preconditioning;  Myocardial reperfusion injury ;  Tight junctions