皮质醇对大鼠肌纤维膜兴奋性及神经肌肉传递的影响。

The effect of cortisol on the excitability of the rat muscle fibre membrane and neuromuscular transmission.

作者信息

Dlouhá H, Vyskocil F

出版信息

Physiol Bohemoslov. 1979;28(6):485-94.

Abstract

The present experiments show that cortisol when applied in vitro, exerted two different effects on the electrical excitability of the diaphragm muscle fibre membrane and on the neuromuscular transmission depending on the concentration used. At low concentrations (2.5X10(-6) mol.l-1) it potentiated action potentials, increased resting membrane polarization by 3--4 mV and did not affect neuromuscular transmission. Higher concentrations (10(-2) mol.l-1) suppressed the action potential to a certain extent, depolarized the muscle fibre membrane by 6 mV and reduced the amplitudes of m.e.p.p.s and e.p.p.s as well as those of iontophoretically evoked acetylcholine potentials. It was concluded that the effect of low concentrations of cortisol is primary and is probably due to the enhancement of resting membrane permeability for K+ ions and to the changes in ion channels. Cortisol in high doses increased muscle oxygen consumption, so that its suppressing effect might be due to inhibition of energy metabolism.

摘要

目前的实验表明，皮质醇在体外应用时，根据所使用的浓度，对膈肌肌纤维膜的电兴奋性和神经肌肉传递产生两种不同的影响。在低浓度（2.5×10⁻⁶mol·L⁻¹）时，它增强动作电位，使静息膜极化增加3 - 4mV，并且不影响神经肌肉传递。较高浓度（10⁻²mol·L⁻¹）在一定程度上抑制动作电位，使肌纤维膜去极化6mV，并降低微小终板电位和终板电位的幅度以及离子导入诱发的乙酰胆碱电位的幅度。得出的结论是，低浓度皮质醇的作用是原发性的，可能是由于静息膜对钾离子通透性的增强以及离子通道的变化。高剂量的皮质醇增加肌肉耗氧量，因此其抑制作用可能是由于能量代谢的抑制。