4-Aminopyridine and tetraethylammonium-induced changes in action potentials of unmyelinated axons.

N I Radicheva, V B Kolev
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Abstract

The effects of different concentrations of 4-aminopyridine (4-AP) and tetraethylammonium (TEA) on the intra- and extracellular action potentials (ICAPs, ECAPs) of unmyelinated axons of Lumbricus terrestris were studied. The results showed different sensitivity of the axons to both potassium current blockers (4-AP and TEA), added to the medium. 4-AP led to spontaneous and single stimulus- evoked repetitive activity, manifested as a slow "burst" action potential propagation like "plateau" ICAP with oscillations. The ICAP duration of the TEA-treated axons increased mainly at the expense of the repolarization phase which reflected the increased duration of the ECAP recorded at long radial distances. The amplitude of the ICAPs after treatment with both blockers was decreased to 20% as compared to the controls (untreated axons) and ECAPs decreased to 40% in the TEA-treated axons. The conduction velocity (CV) of the action potentials was not significantly changed. The calculated total ionic current during the action potential upon TEA treatment was decreased and the duration of the outward phase was prolonged.

4-氨基吡啶和四乙基铵诱导无髓鞘轴突动作电位的变化。
研究了不同浓度的4-氨基吡啶(4-AP)和四乙基铵(TEA)对地蚓无髓轴突细胞内和细胞外动作电位(ICAPs, ECAPs)的影响。结果表明,轴突对加入钾电流阻滞剂(4-AP和TEA)的敏感性不同。4-AP导致自发性和单刺激诱发的重复性活动,表现为缓慢的“突发”动作电位传播,类似“高原”ICAP,伴有振荡。经tea处理的轴突的ICAP持续时间增加主要是以复极化期为代价的,这反映了长径向距离记录的ECAP持续时间的增加。与对照组(未处理的轴突)相比,两种阻滞剂治疗后的icap幅度下降了20%,而在茶处理的轴突中,ecap下降了40%。动作电位的传导速度(CV)无明显变化。经TEA处理的动作电位期间计算的总离子电流减小,外向相持续时间延长。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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