金褐霉素（Aureofuscin）对神经末梢...

By means of the intracellular recording technique, the effect of aureofuscin (20 micrograms/ml, oversaturation solution) on the ACh release from motor nerve terminals and on muscle cell membrane potential were investigated in phrenic nerve diaphragm preparations of the mice. The results showed that (a) aureofuscin reduced the resting membrane potential of the muscle cell slightly; (b) the frequency of miniature end-plate potentials and the mean quantal content of end-plate potentials increased at first and then recovered approximately to the control level; (c) the depolarization produced by aureofuscin in the muscle cell membrane was reversible and the aureofuscin-invoked facilitation in miniature end-plate potential discharges was Ca(2+)-dependent; and (d) aureofuscin did not block neuromuscular transmission.     

ω-芋螺毒素及其在 Ca2+通道研究中的应用

ω-芋螺毒素(ω-CTX)——一组含25—29个氨基酸残基的亲水肽,已能人工合成,是近年从海产软体动物中发现的专一作用于电压敏感性钙通道的突触前阻断剂,利用它和双氢吡啶类药物可将细胞膜的 Ca²⁺通道区分为不同亚型.     

Four types of potassium currents in motor nerve terminals of snake

The experiments were perfomed on transvcrsus abdominis muscle of Elaphe dione by subendothelial recording. The results indicate that in snake motor nerve endings there exist four types of K* channels, i.e. voltage-dependent fast and slow K channels, Ca2 -activated K channel and ATP-sensitive K channel, (i) The typical wave form of snake terminal current was the double-peaked negativity in standard solution. The first peak was at-tributed to Na influx (INa) in nodes of Ranvier. The second one was blocked by 3, 4-aminopyridine (3, 4-DAP) or te-traethylammonium (TEA), which corresponded to fast K outward current (IKF) through the fast K* channels in terminal part, (ii) After IKF as well as the slow K current (IKS) were blocked by 3, 4-DAP, the TEA-sensitive Ca2 -dependent K current (IK(Ca)) passing through Ca2 -activated K channel was revealed, whose amplitude depended on [K ]and [Ca2 ] It was blocked by Ba2 , Cd2 or Co2 . (iii) IK.F and IK(Ca) were blocked by TEA, while IK.S was retained. It     

金褐霉素(Aureofuscin)对神经末梢的递质释放和肌细胞膜的作用

利用细胞内微电极记录,在小鼠离体膈神经膈肌标本上观察了金褐霉素(20μg/ml,过饱和溶液)对运动神经末梢的递质释放和肌细胞膜电位的影响。主要作用是:(1)缓慢降低肌细胞膜的静息电位,这种作用是可逆的;(2)有一促进神经末梢的乙酰胆碱量子释放的时相:提高小终板电位的发放频率和终板电位的平均量子含量,但在持续作用下,它们又恢复至接近对照水平;(3)这种对自发量子释放的作用与胞外 Ca~(2+)有关,(4)不阻遏神经肌肉接头兴奋传递。     

青蒿素衍生物SM486对小鼠运动神经末梢钠,钾流的抑制

青蒿素的某些衍生物已被作为救治脑型和抗药性疟疾的首选药物应用于临床，其中，一个含氮的水溶性衍生物ＳＭ４８６在动物实验中显示局部麻醉效应。本文报告它对运动神经末梢的Ｎａ＾＋，Ｋ＾＋通道的作用，实验于小鼠胸三角肌标本上进行，借助于一水浸物镜在放大４００倍显微镜下将微电极插至表层神经束的周鞘下间隙，记录神经末梢膜电流。