摘要目的 探讨大鼠心肌在体缺血再灌注(IR)损伤后细胞膜钙转运通道蛋白的mRNA变化对钙超载的作用。方法 12只SD大鼠按随机数字法分为IR组和对照组。IR组通过结扎（缺血20 min）后松解(再灌注60 min)前降支造成心肌IR,对照组则免除结扎松解前降支。应用生理记录仪连续监测两组大鼠缺血开始前及再灌注60 min后心率、平均动脉压等血流动力学指标。全自动生化仪检测缺血前及再灌注60 min后两组大鼠血钙及肌钙蛋白T(cTnT)的水平。荧光定量PCR检测再灌注60 min后两组大鼠左心室缺血区和右心室心肌细胞膜钙转运通道蛋白即心肌细胞膜钠钙交换器1(NCX1)，L型钙通道(LVDCC)α-1C和胞膜钙转运ATP酶1(PMCA1 )mRNA的表达。结果两组大鼠缺血前的心率、平均动脉压均高于再灌注60 min后，而两组间缺血前和再灌注60 min后的心率、平均动脉压差异则无统计学意义。两组血浆Ca2+浓度在缺血前与再灌注60 min后差异无统计学意义，同时间点两组之间的差异也没有统计学意义。缺血前IR组与对照组血浆cTnT浓度水平相近，缺血60 min后IR组血浆cTnT浓度较对照组升高[(4.29±2.22) μg/L比(1.62±0.60)μg/L，P=0.031]；两组血浆cTnT浓度在缺血前与再灌注60 min后差异也有统计学意义（均P＜0.05）。NCX1，LVDCCα-1C和PMCA1的mRNA表达在再灌注60 min后同心室两组间和同组内左右心室之间的差异均无统计学意义（NCX1：对照组左心室为50±4，右心室为47±9；IR组左心室为55±6,右心室为53±11；LVDCCα-1C:对照组左心室为33±7，右心室为30±7；IR组左心室为28±3，右心室为37±5；PMCA1，对照组左心室为70±10,右心室为53±11；IR组左心室为66±12，右心室为78±8;均P＞0.05）。结论 大鼠在体心肌缺血20 min再灌注60 min后,NCX1、LVDCCα-1C和PMCA1的mRNA表达水平均无显著改变，提示钙超载并非由细胞膜钙转运通道蛋白数量改变引起。

abstractsObjective To investigate the effect of altered mRNA expression of sarcolemmal calcium transporting channel proteins in rat myocardial ischemia reperfusion injury (IR)in vivo on calcium overload.Methods Twelve SD rats were randomized into IR and control groups. LAD coronary artery was ligated for 20 min (ischemia) then released for 60 min (repeffusion) in IR group but not in the control group. In both groups,physiologic recorder was used for continuous measurement of bemodynamic parameters including heart rote and mean arterial pressure; full-automated biochemical analyzer was used to determine the serum calcium and cTnT before ischemia and at 60 min after repedusion; quantitative PCR was used to detect the mRNA expression of sarcolemmal calcium transporting channel proteins (NCX 1, LVDCCα-1C and PMCAI ) in cardiomyocytes of the left ventricle (LV, isehemic area) and right ventricle (RV) at 60 min after reperfusion. Results Two groups did not differ in heart rate and mean arterial pressure either before ischemia or at 60 min after reperfusion, but both showed a reduction in these two parameters at 60 min after reperfusion compared with these before ischemia.There was no statistical difference of two groups in serum calcium before ischemia or at 60 min after reperfusion,or at any given time points between two groups. While the plasma cTnT level was comparable before ischemia between two groups. IR group showed significantly elevated cTnT at 60 min after reperfusion compared with the control group[(4.29±2.22) μg/L vs (1.62±0.60) μg/L, P=0.031]. There was statistical difference of two groups in plasma cTnT level before ischemia compared with this at 60 min after reperfusion(all P＜0.05). At 60 min after reperfusion, there were no differences in mRNA expression of sarcolemmal NCXI, LVDCCα-1C and PMCA1 of same ventricle between two groups or between two ventricles of same group (NCX1 : control group LV 50±4,control group RV 47±9; IR group LV 55±6, IR group RV 53±11 ; LVDCCα-1C: control group LV 33±7, control group RV 30±7; IR group LV 28±3, IR group RV 37±5; PMCA1 : control group LV 70±10, control group RV 53± 11 ; IR group LV 66±12, IR group RV 78±8; all P＞0.05). Conclusion The mRNA expression of NCX,LVDCCα-1C and PMCA1 does not change obviously at 20 min after ischemia and at 60 min after reperfusion in rat heart in vivo, suggesting that the quantity of sarcolemmal calcium transporting channel proteins may not be responsible for calcium overload.