目的 研究静脉麻醉药咪唑安定、依托咪酯、异丙酚及硫喷妥钠对离体灌流心脏收缩力及冠脉流量的影响。方法 以含不同浓度静脉麻醉药的克-汉重碳酸盐缓冲液灌流离体大鼠心脏，测定心率(heart rate,HR)、左室收缩压(left ventricular systolic pressure,LVSP)、左室收缩压最大上升速率(LV+dp/dtmax)、左室舒张压最大下降速率(LV-dp/dtmax)及冠脉流量(coronary flow,CF)。结果 随着各药浓度的升高，LVSP、LV+dp/dtmax、LV-dp/dtmax逐渐降低，在等效浓度的抑制作用硫喷妥钠＞异丙酚＞咪唑安定＞依托咪酯；高浓度的硫喷妥钠和异丙酚减慢心率。硫喷妥钠使CF下降，异丙酚使CF增加，咪唑安定和依托咪酯对CF影响较小。结论 咪唑安定、依托咪酯、异丙酚和硫喷妥钠呈浓度依赖地抑制心肌收缩力，临床使用浓度的异丙酚和硫喷妥钠即有明显的负性肌力作用，异丙酚还可抑制冠状动脉的自动调节机制。%Objective To investigate effects of midazolam, etomidate, propofol and thiopental on contractility and coronary flow of isolated rat hearts. Methods Heart rate, left ventricular systolic pressure (LVSP), (LV+ dp/dtmax), (LV- dp/dtmax) and coronary flow (CF) were assessed in isolated rat hearts perfused with KHB solution containing different concentrations of midazolam, etomidate,propofol and thiopental. Results With increase of concentration, each agent caused progressive but differential decrease in LVSP, LV+ dp/dtmax, LV- dp/dtmax. At equal effective concentration, the rank order of inhibitory potency was thiopental ＞ propofol ＞ midazolam ＞ etomidate. High concentration of propofol and thiopental decreased heart rats. CF was increased by propofol at the concentration greater than 25 μmol/L, but was decreased by thiopental. No changes in CF were induced by midazolam or etomidate. Conclusion The results suggest that midazolarn, etomidate,propofol and thiopental decreased heart contractility in dose-dependent manner. The negative inotropic effect of propofol and thiopental is greater than that of midazolam and etomidate. Propofol, at clinically relevant concentrations, may affect autoregulation by causing coronary vasodilation.
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