The Effect Of Urocortin? Postconditioning Against Ischemic Reperfusion On Cardiac Function And Mitochondrial Cardiolipin Content In Isolated Rat Heart

Objective: To observe the effect of Urocortin? postconditioning against ischemic reperfusion on cardiac function and mitochondrial cardiolipin content in isolated rat heart,in order to further reveal the mechanism of myocardial protection by Urocortin? postconditioning.Methods: Ischemic reperfusion injury was prepared using the Langendorff isolated heart perfusion system.72 healthy SD rats were randomly divided into four groups: normal group(Nor group),Ischemia group(I/R group),Urocortin ? postconditioning group(Ucn ? group),5-HD antagonism group(5-HD+ Ucn ? group).Nor group: Kerbs-Henseleit(K-H)buffer was perfused continuously for 155 minutes.I/R group: K-H buffer was perfused for 20 min,and then cardiac ischemia was induced for 40 minutes before 95 min reperfusion was exerted.Ucn ? group: K-H buffer was perfused for 5 min and K-H containing Ucn? was administrated for 30 min followed by 60 min reperfusion.5-HD+Ucn? group: K-H buffer containing 5-HD before Ucn? postconditioning was used for 5 min,the rest managements were the same with Ucn? group.The following indexes of the four groups were evaluated at the end of equilibrium,before ischemia and at the termination of reperfusion respectively:(1)heart rate(HR),left ventricular end-diastolic pressure(LVDEP),left ventricular developed pressure(LVDP)and maximum dp/dt(dp/dtmax),coronary blood flow(CF)were used to indicate heart function;(2)Mitochondria from ventricular tissues were isolated and extracted mitochondrial phospholipids High performance liquid chromatography(HPLC)was used to detect the content of mitochondrial cardiolipin..Results:1.Indexes of heart function:There was no significant difference in HR,LVDP,LVEDP,dp/dt and CF indexes between T1 and T2 in each group and all the groups(P > 0.05),The cardiac function of T3 in each group was lower than that of T1 and T2(P<0.05 or P< 0.01);Compared with Ucn?group of T3 point the HR,LVDP,LVEDP,dp/dtmax and CF were less than Nor group(P<0.05 or P<0.01),but better than 5-HD+Ucn?group and I/R group(P<0.05 or P< 0.01),There was difference between I/R group and 5-HD+Ucn? group in cardiac function indexes(P<0.05).2.Changes of mitochondrial cardiolipin content:There was no significant difference in mitochondrial cardiolipin content between T1 and T2 in each group and all the groups(P>0.05),The mitochondrial cardiolipin content of T3 in each group was lower than that of T1 and T2(P<0.05 or P< 0.01);Compared with Ucn?group of T3 point the mitochondrial cardiolipin content was less than Nor group(P<0.05 or P<0.01),but higher than 5-HD+Ucn?group and I/R group(P<0.05 or P<0.01),There was difference between I/R group and 5-HD+Ucn? group inmitochondrial cardiolipin content(P< 0.05).Conclusion: 1.Urocortin? postconditioning can increase the contractile force of ischemic myocardium,decrease the end diastolic pressure,increase cardiac output,improve the function of damaged heart.2.Urocortin? postconditioning improve the damaged heart function may be associated with preserved the mitochondrial cardiolipin content.The mechanism may be related to the opening of mito-KATP channels.