Myocardial Protective Effects Of Hypothermia And Toadfish Against Ischemia/reperfusion Injure In Rabbits

Objective To investigate the protective effects of hypothermia and toadfish on myocardium against ischemia/reperfusion injury.Methods Thirty Zealand rabbits were randomly divided into 5 equal groups with 6 rabbits in each group:A control group;B ischemia reperfusion group;C hypothermia group;D toadfish group;E hypothermia+toadfish group.Temperature,heart rate (HR),maximum positive and negative change in pressure (±dp/dt_max) ,left ventricular systolic pressure (LVSP) were recorded before ,during and at the end of myocardial ischemia and at 30,60,90,120min of reperfusion.Blood samples were taken for determination of plasma SOD,MDA,FFA and LD at the end of reperfusion.At the end of the experiment,myocardial tissue 50-80mg was obtain from ischemia area for determination of myocardial ATP,SOD,MDA,FFA and LD activies and election microscpic examination.Resultl.Haemodynamics myocardial functional parameters were similar among the six groups before the ligation of LAD (p<0.05).Campared with B group, in the reperfusion period,C and E group can markedly decrease LVSP (p<0.05). There was no difference of LVSP between D group and B group (p<0.05),but when ischemia 30 minutes and reperfusion 120 minute the LVSP of D group was higher than that of B group (p<0.05). ±dp/dt_max: ±dp/dt_max were significantly lower in the C group and E group as compared with the B group. While ±dp/dt_maxwas markedly higher in the D group when compared with B group.2.SOD,MDA,FFA,LD The level of MDA,FFA and LD in C,D and E groups were significant lower than B group (p<0.05).But the level of SOD and myocardial ATP in C,D,E group were higher when compared with B group (p<0.05).3.Infarct size IS was significant lower in C,D and E group vs B group [(19.33 +1.63)%,(26.17±2.04)%,(15.33±2.42)% vs (35.67 + 3.72)%, p<0.05].IS in C and E group was lower than that in D group,while compared with D group,E group was significant decrease IR (p<0.05).4.Ultrastructure The myocardial ultrastructure shows severe damage in B group, attenuated damage in C and D group,and nearly normal structure in E group. Conclusion1. Hypothermia has obviously protective effects on myocardium against ischemia/reperfusion injure .2. Toadfish has protective effects on myocardium against ischemia/reperfusion injure .3. The protective effects of hopothermia and toadfish on myocardinm against ischemia/reperfusion injury was significantly different in haemodynamics,which perhaps was relative to their diffferent protective mechanism.4. Combination of hopothermia and toadfish provides better protection.