钙蛋白酶抑制剂对烧冲复合伤大鼠心功能的作用

Role of calpain inhibitor in improving cardiac function in burn-blast combined injury rats

目的探讨钙蛋白酶抑制剂对烧冲复合伤大鼠心功能的作用。方法 72只雄性SD大鼠随机分为3组各24只;对照组大鼠置于37℃水中12s;复合伤组大鼠采取爆炸+94℃水烫伤方法形成烧冲复合伤;钙蛋白酶抑制剂组大鼠以相同方法形成烧冲复合伤后,腹腔注射钙蛋白酶抑制剂MDL28170(24mg/kg)。于伤后24、48、72h分别取各组大鼠8只进行研究。测定不同时间大鼠左室射血分数(left ventricular ejection fraction,LVEF)、左心室短轴缩短指数(left ventricular fractional shortening index,LVFS);检测血清肌钙蛋白Ⅰ(cardiac troponin Ⅰ,cTnⅠ)、肌酸激酶同工酶(creatine kinase isoenzyme,CK-MB)水平;Tunel染色法检测心肌组织细胞凋亡(计算凋亡指数);荧光光度法检测心肌组织中钙蛋白酶和caspase-3活性;原子吸收光谱仪测定心肌组织细胞Ca^(2+)水平。结果复合伤组大鼠24、48、72h时,以及钙蛋白酶抑制剂组48h时LVEF、LVFS均低于对照组(P<0.05),复合伤组大鼠24h时LVEF与钙蛋白酶抑制剂组比较差异无统计学意义(P>0.05),其余时间点LVEF、LVFS均低于钙蛋白酶抑制剂组(P<0.05);复合伤组24、48、72h时cTnⅠ、CK-MB及钙蛋白酶抑制剂组24、48h时cTnⅠ、CK-MB均高于对照组(P<0.05),复合伤组24h时cTnⅠ、CK-MB,以及48h时cTnⅠ,72h时CK-MB均高于钙蛋白酶抑制剂组(P<0.05),其余时间点复合伤组cTnⅠ、CK-MB与钙蛋白酶抑制剂组比较差异均无统计学意义(P>0.05);24、48、72h时钙蛋白酶抑制剂组、复合伤组心肌凋亡指数均高于对照组(P<0.05),钙蛋白酶抑制剂组48、72h时心肌凋亡指数低于复合伤组(P<0.05);复合伤组24、48、72h时以及钙蛋白酶抑制剂组伤后48、72h时心肌钙蛋白酶活性均高于对照组(P<0.05),24h时心肌钙蛋白酶活性高于钙蛋白酶抑制剂组(P<0.05);各时间点复合伤组和钙蛋白酶抑制剂组caspase-3活性均高于对照组(P<0.05),48、72h时复合伤组高于钙蛋白酶抑制剂组(P<0.05);复合伤组24h时心肌Ca^(2+)水平高于对照组和钙蛋白酶抑制剂组(P<0.05)。结论钙蛋白酶抑制剂可通过抑制钙蛋白酶活性而减轻心肌细胞凋亡,改善烧冲复合伤后心功能。

Objective To study the role of calpain inhibitor in improving cardiac function in burn-blast combined injury rats.Methods Seventy-two male SD rats were randomly divided into control group,burn-blast group and calpain inhibitor group,with 24 rats in each group.Control group was bathed in 37℃ warm water for 12s.Burn-blast group was treated with explosion＋94℃ hot water scalds for 12s.Calpain inhibitor group was intraperitoneally injected with calpain inhibitor MDL28170 24mg/kg after burn-blast combined injury.Eight rats were selected from each group at 24,48 and 72h after injury.Left ventricular ejection fraction（LVEF）,left ventricular fractional shortening index（LVFS）,serum cardiac troponin I（cTnI）and creatine kinase isoenzyme（CK-MB）were detected,myocardial apoptosis was detected by Tunel method,calpain and caspase-3 activity were detected by fluorescence spectrophotometry,and Ca^2＋level was measured by atomic absorption spectrometer at different time points in three groups.Results Both LVEF and LVFS were significantly lower at 24,48 and 72h in burn-blast group and at 48h in calpain inhibitor group than those in control group（P〈0.05）,at 48 and 72h in burn-blast group than those in calpain inhibitor group（P〈0.05）,and there was no significant difference in LVEF at 24h between burn-blast group and calpain inhibitor group（P〉0.05）.The levels of cTnI and CK-MB were significantly higher at 24,48 and 72h in burn-blast group and at 24 and 48h in calpain inhibitor group than those in control group（P〈0.05）,while the levels of cTnI and CK-MB at 24h,cTnI level at 48hand CK-MB at 72h in burn-blast group were significantly higher than those in calpain inhibitor group（P〈0.05）,and there were no significant differences in the levels of cTnI and CK-MB on the other time points between burn-blast group and calpain inhibitor group（P〉0.05）.The myocardial apoptosis indexes were significantly higher in calpain inhibitor group and burn-blast group than those in control group at 24,48 and 72h（P〈0.05）,and in burn-blast group at 48 and 72h than those in calpain inhibitor group（P〈0.05）,Calpain activities were significantly higher at 24,48 and 72h in burn-blast group and at 48 and 72h in calpain inhibitor group than those in control group（P〈0.05）,and the calpain activity was significantly higher at 24h in burn-blast group than that in calpain inhibitor group（P〈0.05）.Caspase-3 activities were significantly higher at all time points in burn-blast group and calpain inhibitor group than those in control group,and at 48 and 72h in burn-blast group than those in calpain inhibitor group（P〈0.05）.The level of Ca^2＋was significantly higher at 24h in burn-blast group than that in control group and calpain inhibitor group（P〈0.05）.Conclusion Calpain inhibitor can improve cardiac function by reducing myocardial apoptosis through inhibiting calpain activity in burn-blast combined injury rats.