IS CHANNEL BLOCKING EFFECT CAUSED BY GENERAL ANESTHETICS PARTICIPATE IN MEMBRANE FLUIDATION?

全身麻醉有几种可能的机制，包括离子通道电导的变化。增加膜流动性，改变对神经递质的反应。众所周知，乙醇可以增强膜的流动性，并在脂质双层中增强。苯丙醇能提高膜电容(Cm)。另一方面，烷基乙酸酯降低了小鼠的膜流动性。氟烷为吸入全麻，异丙酚和硫喷妥钠为静脉全麻，三种麻醉剂均对心脏L型钙通道有抑制作用。但这些全身麻醉药对CM的作用仍不确定。本研究旨在测定麻醉引起的膜时间常数(Tau_M)的变化，当与输入阻力(R_t；in&gt；)减小或不变时，膜时间常数(Tau_M)可用来推断C_m的变化。观察了氟烷、异丙酚和硫喷妥钠对单个豚鼠血管椭圆形心肌细胞膜电容(C_M)的影响。氟烷的cm略有下降。而异丙酚和硫喷妥钠则有增加的趋势。由于这三种麻醉剂对L型钙通道均有抑制作用，故推测氟烷与其他两种静脉麻醉剂对离子通道的抑制作用机制可能不同。

There are several possible mechanisms of general anaesthesia including the change of conductance in ionic channels. increased membrane fluidity, and altered responses to neurotransmitters . Ethanol is known to enhance membrane fluidity, and in lipid bilayers. beuzyl alcohol was shown to raise membrane capacitance (C_m). On the other hand, alkyl acetates decreased membrane fluidity in mice. Halothane is an inhaled gemeral anaesthetic, and propofol and thiopental are intravenous general anaesthetics, and all of these three anaesthetics have an inhibitory effect on L-type calcium channel of cardiac. But the effect of these general anaesthetics on C_m is still uncertain. This study was carried out to measure anaesthetic- induced changes in the membrane time constant (tau_m) , which, when coupled with decreased or unchanged input resistance (R_<In>), can be used to deduce changes in C_mThe effects of halothane, propofol and thiopental on membrane capacitance (C_m) in a single guinea-pig veutricular myocyte were examined. Halothane showed slight decrease in Cm. However, propofol and thiopental showed increase in Cm. Because these three anaesthetics all have an inhibitory effect on L-type calcium channel, it is suggested that there would be different mechanisms in the inhibitory effect on ionic channels between halothane and other two intravenous aiiaesthetics other than C_m, alternation.