【摘要】 目的探讨细胞膜钠钙交换蛋白(NCX)在心肌缺血预适应及药物诱导预适应中的作用及可能的信号转导途径。方法培养乳鼠心肌细胞随机分为缺血/再灌注组、缺血预适应组、腺苷预处理组、钙调素依赖蛋白激酶Ⅱ(CaMKⅡ)抑制剂KN-93+缺血预适应组、KN-93+腺苷预处理组及对照组。各组乳酸脱氢酶(LDH)漏出量用生化法测定(n=5),钠钙交换蛋白mRNA表达以半定量RT-PCR检测(n=5),NCX活性以液闪仪测定Na+依赖的45Ca2+摄取率表示(n=5)。结果(1)缺血/再灌注组LDH漏出量显著增加(P<0·05),缺血预适应及腺苷预处理组LDH漏出量均显著降低(P<0·05);KN-93预作用后,缺血预适应及腺苷预处理组LDH漏出量均显著增加(P<0·05)。(2)缺血/再灌注组NCX45Ca2+摄取率比对照组高(P<0·005)。缺血预适应及腺苷预处理组较缺血/再灌注时NCX45Ca2+摄取率显著低(P<0·05),且腺苷预处理组NCX45Ca2+摄取率较缺血预适应组更低(P<0·05)。KN-93+缺血预适应组与缺血/再灌注组NCX45Ca2+摄取率差异无统计学意义,KN-93+腺苷预处理组较缺血/再灌注组NCX45Ca2+摄取率低(P<0·05)。(3)缺血/再灌注组NCXmRNA的表达比对照组显著高(P<0·05);缺血预适应及腺苷预处理组NCXmRNA的表达均显著低(P<0·05);KN-93处理后缺血预适应组及腺苷预处理组NCXmRNA的表达水平显著高(P<0·05),且腺苷预处理组NCXmRNA的表达较缺血预适应组更高(P<0·05)。结论缺血预适应及腺苷预处理对心肌的保护作用与细胞膜NCX有关,缺血预适应中NCX对心肌损伤保护作用经CaMKⅡ介导,而在腺苷预处理中NCX对心肌损伤保护作用仅部分经CaMKⅡ介导。更多还原

【Abstract】 Objective To investigate the role of sodium-calcium exchanger (NCX) on ischemic preconditioning and pharmacological preconditioning.Methods Cultured rat neonatal cardiomyocyctes were randomly divided into 6 groups: (1) ischemia/reperfusion group (9 h ischemia followed by 1 h reperfusion, I/R), (2) ischemic preconditioning group (1.5 h ischemia/1 h reperfusion+I/R), (3) pharmacologic preconditioning group, adenosine (10 μmol/L) pretreated for 1 h+I/R, (4) calmodulin-dependent protein kinase Ⅱ(CaMKⅡ) inhibitor KN-93 (0.5 μmol/L for 0.5 h)+ischemic preconditioning group, (5) KN-93+pharmacologic preconditioning group, (6) control group. The leakage of intracellular lactate dehydrogenase (LDH) in various groups was determined by biochemical autoanalyzer. Semi-quantitative RT-PCR was employed to measure the mRNA levels of sodium-calcium exchanger. Activity of sodium-calcium exchanger (Na~+-dependent ~ 45 Ca~ 2+ uptake) was measured by liquid scintillation counting.Results (1) Compared to the I/R group, the LDH leakages in both ischemic preconditioning group and pharmacologic preconditioning group were significantly reduced (P<0.05) while significantly increased in the KN-93+ pharmacologic preconditioning group and the KN-93+ischemic preconditioning group (P<0.05).(2)The Na~+-dependent ~ 45 Ca~ 2+ uptake was significantly increased in the I/R group (P<0.05) compared to control group and this increase could be significantly attenuated in ischemic preconditioning group and adenosine pretreatment group (P<0.05). (3)The expression of NCX mRNA in I/R group was also significantly increased (P<0.05) in the I/R group (P<0.05) compared to control group and this increase could be significantly attenuated in ischemic preconditioning group and adenosine pretreatment group (P<0.05), CaMKⅡinhibitor KN-93 significantly abolished these effects in preconditioning group (P<0.05 )and in adenosine pretreated group(P<0.05).Conclusion NCX mediated the cardioprotective effects of ischemic preconditioning and pharmacological preconditioning in the neonatal cardiomyocytes I/R model.更多还原