大鼠在体心肌缺血再灌注损伤组织间液钙离子动态与胞膜钠钙交换体表达

摘要

Objective To detect the dynamics of interstitial calcium and sarcolemal NCX mRNA expression in rat myocardi-al ischemia-reperfusion injury ( IRI) in vivo. Methods Twelve SD rats were randomly divided into IR group and control group. Myocardial interstitial fluid was collected continuously by microdialysis technique and calcium concentration was measured by an atomic absorption spectrophotometer. In IR group,LAD was ligated for 20 min,and then released for 60 min to induce IR model. The left ventricle(ischemic area)and right ventricle were harvested for quantitative PCR of sarcolemal NCX at the end. Serum calcium cTnT were also detected before and after IR. Procedures were the same in control group but no ligating/ releasing LAD. Results The cTnT was elevated significantly in IR group[control vs IR, ng/mL: (1. 62 + 0. 60) vs. (4.29 + 2. 22),P = 0. 031]. Interstitial calcium concentration kept steady during ischemia, while went down sharply at 20 min later in reperfusion. Dialysate calcium concentration in IR group was significantly lower than that in control group[control vs IR,ng/ mL:(224 + 31) vs. (136 + 39),P = 0. 002]. There was no significant difference in both groups for serum calcium before and after experiment. There were no differences in or between groups for sarcolemal NCX mRNA expression. Conclusion In this 20-min myocardial ischemia and 60-min reperfusion injury rat model in vivo , interstitial calcium concentration kept steady during ischemia,while went down sharply after reperfusion, which was not correlated with sarcolemal NCX mRNA expression.%目的 检测大鼠心肌在体缺血再灌注损伤(IR)组织间液钙离子浓度,比较IR前后心肌胞膜钠钙交换体(NCX)mRNA表达水平,探讨其对钙超载的意义.方法 12只SD大鼠随机分为IR组和对照组,以微透析技术连续收集心肌组织间液标本,原子吸收光谱法检测钙离子浓度.IR组通过结扎(20 min)后松解(60 min)冠状动脉前降支造成心肌缺血再灌注,结束时收取左心室缺血区和右心室心肌行NCX mRNA定量PCR检测,实验前后采血检测血钙和肌钙蛋白T(cTnT).对照组免除结扎、松解前降支,其余操作与IR组一致.结果 IR组血浆cTnT浓度显著升高[对照组 vs IR组,ng/mL:(1.62±0.60) vs.(4.29±2.22),P=0.031].IR组心肌组织间液钙离子浓度在缺血期无明显变化,再灌注20 min显著下降,心肌析出液钙离子浓度与对照组存在显著性差异[对照组vs.IR组,ng/mL:(224±31) vs.(136±39),P=0.002].血浆Ca2+浓度实验前后无显著差异.心肌细胞膜NCX mRNA表达水平在组间和组内均无显著差异.结论大鼠在体心肌缺血20 min再灌注60 min,组织间液钙离子浓度在缺血期无明显变化,再灌注期迅速下降,这种变化趋势与胞膜NCX表达无关.