豚鼠迷走神经神经元中一种对蜂毒明肽不敏感的缓慢钙激活钾电流的动力学特性

Kinetic properties of a slow apamin-insensitive Ca(2+)-activated K+ current in guinea pig vagal neurons.

Sah P

Department of Physiology and Pharmacology, University of Queensland, Australia.

J Neurophysiol. 1993 Feb;69(2):361-6. doi: 10.1152/jn.1993.69.2.361.

Abstract

The calcium-activated outward current (gKCa,2) following an action potential was recorded from neurons in the guinea pig dorsal motor nucleus of the vagus (DMV). gKCa,2 was activated after a delay after the action current and had a distinct rising phase in contrast to the apamin sensitive calcium-activated current in rat DMV neurons (gKCa,1). 2. The time course of gKCa,2 was well described by function of the form A*[exp(t/tau 1)-exp(t/tau 2)], where tau 1 = 1.42 +/- 0.05 (SE) s and tau 2 = 555 +/- 24 ms. 3. Increasing calcium influx by firing multiple action currents lead to an increase in the peak amplitude of gKCa,2 with no change in its kinetics. In cells loaded with low concentrations of ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA), gKCa,2 was smaller in amplitude but its time course was similar to that in cells not loaded with EGTA. 4. When preceded by a conditioning influx of calcium, the amplitude and time course of gKCa,2 was identical to one with no conditioning influx. These results show that, after influx of calcium, a potassium current with stereotyped amplitude and kinetics is generated. 5. These data are consistent with the idea that the source of calcium for activation of gKCa,2 is not the extracellular space.

摘要

从豚鼠迷走神经背运动核（DMV）的神经元中记录到动作电位后的钙激活外向电流（gKCa,2）。与大鼠DMV神经元中的蜂毒明肽敏感钙激活电流（gKCa,1）不同，gKCa,2在动作电流出现延迟后被激活，且具有明显的上升相。2. gKCa,2的时间进程可用A*[exp(t/tau 1)-exp(t/tau 2)]形式的函数很好地描述，其中tau 1 = 1.42 +/- 0.05（标准误）秒，tau 2 = 555 +/- 24毫秒。3. 通过发放多个动作电流增加钙内流会导致gKCa,2的峰值幅度增加，但其动力学无变化。在装载低浓度乙二醇双（β-氨基乙基醚）-N,N,N',N'-四乙酸（EGTA）的细胞中，gKCa,2的幅度较小，但其时间进程与未装载EGTA的细胞相似。4. 当有一个预适应的钙内流时，gKCa,2的幅度和时间进程与没有预适应内流时相同。这些结果表明，钙内流后会产生一种具有固定幅度和动力学的钾电流。5. 这些数据与gKCa,2激活的钙源不是细胞外空间这一观点一致。