布比卡因对大鼠心室肌细胞内钙的影响

Effects of bupivacaine on intracellular Ca^(2+) in rat ventricular myocytes

目的:运用激光扫描共聚焦显微镜观察不同浓度的布比卡因对KCl诱导的大鼠心室肌细胞内游离钙离子浓度([Ca2+]i)的影响,进而探讨布比卡因心肌抑制作用的可能机制。方法:培养新生SD大鼠心室肌细胞,将培养的心室肌细胞随机分为4组,分别为对照组(C组)、10μmol/L布比卡因组(B1组)、50μmol/L布比卡因组(B2组)、100μmol/L布比卡因组(B3组)。各组细胞均用钙荧光指示剂Fluo-3/AM染色,运用激光扫描共聚焦显微镜动态观察单个心室肌细胞内钙荧光强度(fluorescent intensity,FI)的变化。结果:与对照组比较10μmol/L的布比卡因对KCl诱导的大鼠心室肌细胞内钙FI变化无明显影响(P>0.05),50μmol/L和100μmol/L的布比卡因则明显抑制KCl诱导的钙离子跨膜内流(P<0.05);抑制程度B3组>B2组(P<0.05)。结论:低浓度的布比卡因对KCl诱导的大鼠心室肌细胞内[Ca2+]i的变化无明显影响,高浓度则明显抑制钙离子跨膜内流。布比卡因呈浓度依赖性抑制兴奋收缩耦联时心室肌细胞内游离钙离子内流,可能是其心肌抑制作用的原因之一。

AIM： To observe the effects of bupivacaine at different concentrations on intracellular free C2^＋ concentration（ [ C^2＋]i ） in isolated rat ventricular myocytes induced by KCl using laser scanning confocal microscope（LSCM）, and to investigate the mechanism of cardiotoxicity of bupivacaine. METHODS： The cultured ventricular myocytes of newborn rats were divided randomly into 4 groups： the control group （group C）, the group of bupivacaine at 10 μmol/L （group B1 ）, the group of bupivacaine at 50 μmol/L （ group B2 ） and the group of bupivacaine at 100 μmol/L （group B3 ）. The fluorescent intensity （FI） of intmeellular C^2＋ in single cultured cardiomyocytes of newborn rats loaded with Fluo-3/AM was observed by LSCM in order to compare the effects of bupivacaine at different concentrations on the change of [ C2^＋ ]i induced by KCI. RESULTS： There was no difference in the changes of intracellular Ca^2＋ FI in rat ventricular myocytes induced by KCI in group B1 compared with those in group C（P〉0.05）. Intracellular Ca^2＋ FI in rat ventricular myocytes induced by KCI was inhibited significantly in group B2 and B3 compared with that in group C （ P 〈 0.05）. CONCLUSION： There is no significant effect of bupivacaine at low concentration on intracellular Ca^2＋ in rat ventricular myocytes induced by KCI. Bupivacaine at high concentraton could significantly inhibit the effects on [ Ca^2＋ ]i in rat ventricular myocytes induced by KCl. Bupivacaine could inhibit Ca^2＋ transsarcolemmal influx in isolated rat ventricular myocytes dosedependently, which may in part explain its negative inotropic effect.