Long-term hypothermic preservation of rat hearts with diazoxide-containing celsior solution

Abstract

Objecltve To assess the effectiveness of diaxoxide-containing Celsior cardioplegia solution for long-term preservation of the Rat Hearts in vitro,and to study the potential mechanisms of diazoxide,an ATP-sensitive mitochondrial potassium channel opener in reducing the ischemia-reperfusion injury.Methods The modified Heron's technique for heterotopic cervical heart transplanation in rat models was used.Before transplantation,SD rats were randomized into control groups ,in which the donor rats'hearts were stored in Celsior cardioplegia solution at 4 C for 5 or 10 hours,experimental groups,in whieh diazoxide(30yumol/L)was to Celsior solurtion for 5 or 10hours,and a group of antagonism ,in which 5-hydroxydecanoate(5-HD),a mito-KATPC inhibitor,was added to the solution(in 100 umol/L) used in the experimental groups for 5 hours.Samples of the miyocardium were collected at 5 min,1 week ad 3 months after heart transplantation and were messured for the level of melondialdehyde(MDA),the activities of superoxide dismutase(SOD),Na+-AT- Pase and Ca2+-ATPase.The gene expresssion of TNF-a,Fas/FasL and Caspase-3 was analyzed.Apoplotic cardiomyocytes were detected by TdT-mediated dUTP nick end Labeling(TUNEL)technique.The myocardial ultrastructre was also observed.Results The experi-mental groups were much superior to the control groups in the measurements at 5 minutes and 1 week after beart transplantation,for whichthe donor rats 'bearts were preserved for the same period.The superioroties were maintained at 3 months,The level of MDA was decreased significantly,the netivites pf SOD and Na+-k+-ATPase were enhanced,gene expression of FasL and Tnf-a was reduced with dlmmide.The effectss of diazoxide were eliminated by 5-HD.Modeet si[eropmotoes were observed in one experimental group in which the donor rate'hefts were preserved for 10 hours ,as compared with one control group in which the donor rats'hearts were preserved for 5 houm.Histologically,the myo cardial ultrastructure was preserved relatively well in teh experinental groups and in the 5-hourpresera-tion control group.Conclusion Diazoxide-containing Celsior solution provides longer protection for the donr rats'hearts than well-es-tablished period of 4 to 6 hours.These findings indicate that the mechanisme for diazoxide to alleviate ischemoia-reperfusion injury to the rat myocardium may be associated with its roles in the myocardal protection,which involving early opening of mito-KatpC, a process providing protection for mitochondrial structure and function,enrly in-hilaition of apoptosis induced by axidative stress,prohibition of cal-cimn overloadinthe cells.reduction of the expression 0f apoptosis-related genes.The heartsmay be preserved safely and effectovely in dimoxide-containing Celsior cardioplegia solution for 10 hours. Key words: Diazoxide Myocmdial reperfusion injury Heart transplantation Apoptosis