Joy R M, Vogel S M, Narahashi T
Department of Pharmacology and Toxicology, School of Veterinary Medicine, University of California, Davis 95616.
Neuropharmacology. 1987 Aug;26(8):1223-9. doi: 10.1016/0028-3908(87)90273-5.
Studies were carried out to determine whether the insecticide, lindane, influenced calcium-mediated electrical activity or release of neurotransmitter in vitro. In neuroblastoma cells, lindane (1-100 microM) did not appreciably modify action potentials elicited in normal or sodium-free solutions nor did it have a significant effect upon either transient or sustained-type calcium channels. Exposure of cutaneous pectoris neuromuscular junctions of the frog to 100 microM lindane increased spontaneous release of transmitter. In neuromuscular junctions perfused with 0.5 mM Ca++/6 mM Mg++ Ringer (low quantal release conditions), lindane increased evoked release of transmitter. The absolute increase amounted to just less than one quanta and the extent of the increase was inversely proportional to the mean number of quanta released by the nerve terminal before exposure to lindane. No effect on release of transmitter could be demonstrated when neuromuscular junctions were perfused in normal Ringer. Exposure of neuromuscular junctions to 100 microM lindane also decreased the amplitudes of miniature end-plate potentials. Amplitudes of responses to iontophoretically-applied acetylcholine (ACh) were similarly affected, suggesting that the decrease in amplitudes of miniature end-plate potentials was a reflection of decreased sensitivity of the end-plate to ACh. At neuromuscular junctions of the cutaneous pectoris of the frog, lindane appeared to produce two major effects. Presynaptically, it produced changes in spontaneous and evoked release of transmitter that were consistent with a small increase in free intracellular concentration of Ca++. Postsynaptically, it reduced the sensitivity of the end-plate to ACh.
开展了多项研究以确定杀虫剂林丹是否会在体外影响钙介导的电活动或神经递质的释放。在神经母细胞瘤细胞中，林丹（1 - 100微摩尔）并未明显改变在正常溶液或无钠溶液中引发的动作电位，对瞬时型或持续型钙通道也没有显著影响。将青蛙胸大肌神经肌肉接头暴露于100微摩尔的林丹中会增加递质的自发释放。在灌注了0.5毫摩尔钙离子/6毫摩尔镁离子的林格氏液（低量子释放条件）的神经肌肉接头中，林丹增加了递质的诱发释放。绝对增加量略少于一个量子，且增加程度与暴露于林丹之前神经末梢释放的量子平均数成反比。当神经肌肉接头在正常林格氏液中灌注时，未显示出对递质释放有影响。将神经肌肉接头暴露于100微摩尔的林丹中还会降低微小终板电位的幅度。对离子电泳施加乙酰胆碱（ACh）的反应幅度也受到类似影响，这表明微小终板电位幅度降低反映了终板对ACh的敏感性降低。在青蛙胸大肌的神经肌肉接头处，林丹似乎产生了两种主要作用。在突触前，它引起递质自发和诱发释放的变化，这与细胞内游离钙离子浓度的小幅增加一致。在突触后，它降低了终板对ACh的敏感性。
