Relationship Between Protective Effects Of Sevoflurane Preconditioning On Myocardium And Connexin43in Isolated Rat Hearts

Objective To investigate the protective effects of sevoflurane preconditioning on cardiomyocyte and Connexin43in isolated rat hearts.Methods Thirty-two male Wistar rats were randomly assigned into4groups (n=8each):group I control(group C); group II sevoflurane preconditioning(group S). Moreover, in order to estimate the effects of sevoflurane, group S was divided into3groups according to the volatile concentration of sevoflurane:group S1with1.2%sevoflurane, group S2with2.4%sevoflurane and group S3with3.6%sevoflurane.The animals were anesthesized with intraperitoneal pentobarbital40mg/kg.The hearts were immediately removed and purfused with K-H solution aerated with95%O2and5%CO2at37℃in a Langendorff apparatus.After purfused with K-H solution for30minutes,hearts in group C were purfused with K-H solution continuously for20minutes while hearts in group S were purfused with K-H solution saturated with different concentrations of sevoflurane for15minutes followed by5minutes washout before ischemia.All the hearts were made globally ischemic for40min followed by60min reperfusion. Heart rate(HR), Left ventricular developed pressure(LVDP),+differential pressure timemaxium (+dp/dtmax) and-differential pressure timemaxium(-dp/dtmax) were measured after equilibration,immediately before ischemia,and at30and60minutes reperfusion.After repurfusion,some apex tissues of heart were stained by HE dyeing for observation of histopathology with light microscope,tissues of left ventricle were used for immunohistochemisty to measure the expression and distribution of Connexin43.The integrated optical density (IOD) of Connexin43were measured by a software named Image-pro Plus6.0.Results There were no significant o differences in HR, LVDP,+dp/dtmax and-dp/dtmax before hearts stopped beating in all groups (P>0.05); Compared with group C, cardiac function were significantly better, but the expression of Connexin43were not apparently increased in group S (P>0.05); HR, LVDP,++dp/dtmax and-dp/dtmax were reduced in group S1and S3than in group S2(P<0.05or0.01) except Connexin43(P>0.05); Less damage to cardiomyocyte was observed in group S,especially in group S2. Conclusion Sevoflurane preconditioning could protect cardiomyocyte from I/R injury, it may be releted to inhibition of redistribution but not dephosphorylation of Connexin43.