钙/钙调蛋白依赖性蛋白激酶Ⅱ抑制剂KN-93加重大鼠离体心脏钙超载损伤

Ca^(2+)/calmodulin-dependent protein kinase Ⅱ inhibitor KN-93 aggravates the calcium paradox-induced heart injury

目的观察钙/钙调蛋白依赖性蛋白激酶Ⅱ(CaMKⅡ)抑制剂KN-93对大鼠离体心脏钙超载损伤的影响。方法采用Langendorff装置进行离体心脏灌流,利用钙反常现象诱发胞内钙超载。32只SD♂大鼠随机分为正常对照组、药物KN-93对照组、钙反常组和KN-93处理组。实验全程记录左心室内压的变化,以左心室舒张末压(LVEDP)和发展压(LVDP)评价心功能,于不同时间点收集冠脉流出液,并测定乳酸脱氢酶(LDH)的含量。实验结束后,采用2,3,5-氯化三苯基四氮唑染色检测心肌梗死面积的变化。结果与正常对照组相比,KN-93(2.5μmol·L^(-1))对正常心脏的左室功能、冠脉流量和心肌梗死面积没有明显影响(P>0.05);与正常对照组相比,钙反常组在复钙灌注结束时LVEDP抬升、LVDP降低,梗死面积达(18±7.2)%,冠脉流量减少,LDH含量增加(P<0.01);KN-93(2.5μmol·L^(-1))处理组与钙反常组相比,心肌梗死面积为(90±4.8)%,LVEDP进一步升高,LVDP消失,冠脉流量明显减少,LDH含量明显增多(P<0.01)。结论 CaMKⅡ抑制剂KN-93加重急性钙超载引起的心肌损伤,这一作用可能与影响CaMKⅡ活性有关。

Aim To investigate the effects of Ca^(2+)/calmodulin-dependent protein kinase Ⅱ inhibitor KN-93 on calcium overload-induced heart injury. Methods Thirty-two isolated rat hearts were randomly divided into the control group,KN-93 control group,calcium paradox group,and calcium paradox with KN-93 treatment group. Left ventricular pressure were recorded,and the heart function was evaluated by the left ventricular end-diastolic pressure( LVEDP) and developed pressure( LVDP). Coronary flow( CF) were collected,and lactate dehydrogenase( LDH) content was determined. Triphenyltetrazolium chloride staining was used to measure the infarct size. Results Compared with the control group,KN-93 at 2. 5 μmol·L^(-1) had no effects on coronary flow,cardiac performance and cell death at the end of perfusion in normal rats( P >0. 05); The hearts of calcium paradox exhibited a decrease in LVDP and CF,meanwhile an increase in LVEDP,LDH,and infarct size of 18 ± 7. 2%( P <0. 01). 2. 5 μmol · L^(-1) KN-93 further increased the levels of LVEDP,LDH and infarct size( P < 0. 01) in Ca^(2+)paradoxical hearts,while it provoked the decline in the CF and LVDP( P < 0. 01). Conclusion The data demonstrates that KN-93 aggravates heart injury in calcium paradox,it also suggests that CaMK Ⅱ is involved in the Ca^(2+)overload-induced heart injury.