异丙酚和硫喷妥钠对大鼠心肌细胞钙离子移动的影响

目的　观察不同浓度异丙酚和硫喷妥钠对氯化钾、异丙肾上腺素和咖啡因诱发的大鼠心肌细胞钙离子移动的影响 ,探讨其心肌抑制作用的机制。方法　用Fluo 3AM钙荧光指示剂染色培养的大鼠心肌细胞 ,在激光共聚焦显微镜下动态观察用药前和使用临床麻醉诱导峰浓度和 5倍诱导峰浓度的异丙酚 (5 0、2 5 0 μmol·L-1)和硫喷妥钠 (10 0、5 0 0μmol·L-1)后 ,氯化钾、异丙肾上腺素和咖啡因诱发的细胞内钙离子荧光强度的变化。结果　诱导峰浓度的异丙酚和硫喷妥钠减弱氯化钾和异丙肾上腺素诱发的钙离子跨膜内流 ,细胞内钙荧光强度的峰值下降 ,与对照组相比差异有显著性 (P <0 0 5 ) ,硫喷妥钠的抑制作用较异丙酚大。 5倍诱导峰浓度的异丙酚和硫喷妥钠使钙离子跨膜内流进一步降低。但两种浓度的异丙酚和硫喷妥钠对咖啡因诱发的细胞肌浆网内储存钙的释放、钙荧光强度的升高均无影响 (P >0 0 5 )。结论　异丙酚和硫喷妥钠呈浓度依赖地抑制电压门控和受体门控性钙通道的开放 ,钙离子跨膜内流 ,降低兴奋收缩耦联时细胞内钙离子浓度 ,这可能是其心肌抑制作用的原因之一 ,而对肌浆网的功能无明显影响

The effects of propofol and thiopental on Ca~(2 ) mobilization in cultured rat ventricular myocytes

AIM To elucidate the direct effects of propofol and thiopental on cardiac contraction by measuring intracellular Ca 2+ concentration change in cultured rat ventricular myocytes. METHOD Ventricular myocytes of neonatal rats were obtained by enzymatic digestion with typsin and were cultured for 4～5 days, then were loaded with Fluo 3AM, a new Ca 2+ indicator. The effects of propofol (50, 250 μmol·L -1 ) or thiopental (100, 500 μmol·L -1 ) on changes of intracellular Ca 2+ fluorescent intensity induced by KCl, isoprenaline or caffeine were investigated. RESULTS Both intravenous anesthetics caused dose dependent inhibit Ca 2+ transsarcolemmal influx induced by KCl and isoprenaline, peak Ca 2+ fluorescent intensity decreased. The inhibitory effect of thiopental was more than propofol at equiopotency. Neither anesthetics altered the amount of Ca 2+ release from intracellular stores in response to caffeine. CONCLUSION The negative inotropic effects of propofol and thiopental, at least in part, may be mediated by a decrease Ca 2+ transsarcolemmal influx though voltage gated and receptor gated calcium channel, but it is not relate to sarcoplasmic reticulum Ca 2+ release.