Erdélyi L, Ilyin V I, Lozovaya N A, Vulfius C A
Department of Comparative Physiology, Attila József University, Szeged, Hungary.
Neurosci Lett. 1990 Sep 4;117(1-2):99-104. doi: 10.1016/0304-3940(90)90126-t.
The effects of intracellular Mg2+ (2-8 mM) upon the transient outward current (the A-current) under normal conditions and under catechol-induced blockage were studied in molluscan neurons by using the voltage-clamp and intracellular dialysis techniques. Identified giant Lymnaea stagnalis L. neurons were investigated at room temperature (20-22 degrees C). When applied intracellularly, Mg2+ caused both time- and dose-dependent shifts of the voltage dependence of the steady-state activation and inactivation of the A-current to more negative membrane potentials. Upon external application, catechol suppressed (5-6 mM) or eliminated (9-10 mM) the A-currents, slowed down the current decay and shifted the activation and inactivation curves to more positive membrane voltages. Intracellular Mg2+ decreased the blocking ability of extracellularly applied catechol, whereas catechol antagonized the Mg2(+)-induced negative shift of the steady-state activation and inactivation curves of the A-currents.
利用电压钳和细胞内透析技术，在软体动物神经元中研究了细胞内镁离子（2 - 8 mM）在正常条件下以及儿茶酚诱导的阻断作用下对瞬时外向电流（A电流）的影响。在室温（20 - 22摄氏度）下对已鉴定的巨大椎实螺神经元进行了研究。当细胞内施加镁离子时，A电流的稳态激活和失活的电压依赖性出现时间和剂量依赖性的向更负膜电位的偏移。当细胞外施加时，儿茶酚抑制（5 - 6 mM）或消除（9 - 10 mM）A电流，减缓电流衰减，并将激活和失活曲线向更正的膜电压偏移。细胞内镁离子降低了细胞外施加儿茶酚的阻断能力，而儿茶酚则拮抗镁离子诱导的A电流稳态激活和失活曲线的负向偏移。
