异丙酚对大鼠心肌细胞钙离子移动及钙通道电流的影响

The effects of propofol on intracellular Ca 2+ mobilization and L type calcium current in rat isolated cardiac myocytes

目的 观察异丙酚对心肌细胞钙离子移动和Ｌ－型钙通道电流（Ｉｃａｌ）的影响。方法 急性分离的大鼠单个心室肌细胞，采用Ｆｌｕｏ－３ＡＭ 钙荧光指示剂和膜片钳技术，观察５０μｍ ｏｌ·Ｌ－ １ 或２５０μｍ ｏｌ·Ｌ－ １异丙酚对高浓度ＫＣｌ或咖啡因所诱发细胞内钙离子浓度的变化，以及对Ｌ－型钙通道电流的影响。结果 ５０μｍ ｏｌ·Ｌ－ １或２５０μｍ ｏｌ·Ｌ－ １ 异丙酚明显减弱ＫＣｌ所诱发细胞内钙离子的增加，浓度越高其减弱作用越明显；而对咖啡因所致胞浆内钙离子的增加无明显影响。使钙通道电流峰值分别较用药前下降２４．８％ 和４９．６％ （Ｐ＜ ０．０５，ｎ＝ ５）。洗去异丙酚后Ｉｃａ 可基本恢复至基础水平。结论 异丙酚的负性肌力作用至少部分是由于其影响心肌细胞胞膜功能，减少钙离子跨膜内流以及抑制细胞膜缓慢内流的Ｌ－钙通道电流所致，而对肌浆网功能似乎无明显作用。

Objective To investigate the effects of propofol on intracellular Ca 2+ mobilization and L type calcium current in rat isolated cardiac myocytes.Methods Using Fluorescent Ca 2+ indicator Fluo 3AM and patch clamp techniques(whole cell mode),we measured the influences of propofol,at 50μmol·L -1 or 250μmol·L -1 ,on the changes of intracellular Ca 2+ concentration induced by high concentraton KCl or caffeine,and L type Ca 2+ current simutaneously in isolated cardiac myocytes in rats.Results 50μmol·L -1 or 250μmol·L -1 propofol attenuated KCl induced calcium influx significantly in dose dependent manner and decreased L type calcium peak current for 24.8% and 49.6% respectively(P<0.05,n=5).Propofol seemed to have no effect on the Ca 2+ increase released by sarcoplasmic reticulum induced by caffeine.Influx of Ca 2+ went back to the basic level after the removal of propofol.Conclusion The negative inotropic effect of propofol seems to be,at least in part,due to decreasing Ca 2+ influx and inhibiting L type Ca 2+ current.And propofol shows little effect on sarcoplasmic reticulum function.