On the simultaneous electrophysiological measurements of neurotransmitter release and perineural calcium currents from frog motor nerve endings.
On the simultaneous electrophysiological measurements of neurotransmitter release and perineural calcium currents from frog motor nerve endings.
复制标题
对青蛙运动神经末梢神经递质释放和神经周围钙电流的同步电生理测量。
DOI：
10.1016/0165-0270(94)00133-2
复制
发表时间：
1995
影响因子：
3
通讯作者：
Silinsky,EM
中科院分区：
文献类型：
--
作者：
Redman,RS;Silinsky,EM
本实验测量了蛙骨骼肌运动神经末梢周围区的钙电流和诱发的乙酰胆碱(ACh)释放(即终板电位EPPS)，以确定同时测量这两种现象的实验条件。在含有低钙(0.9 mM)、高镁(10 MM)和中等浓度钾通道阻滞剂(250μM四乙基铵、100μM 3，4-二氨基吡啶)的溶液中，可以可靠地测量神经周围钙电流。为方便起见，这种解决方案将被称为“钙离子电流”林格。细胞外[Ca~(2+)]~(2+)与正常Ringer溶液中诱发的ACh释放之间的关系的中点附近，Ca~(2+)电流林格液中ACh的平均释放数。因此，对低频运动神经刺激(0.05赫兹)反应的ACh释放被很好地维持，允许同时测量钙电流和诱发的ACh释放。细胞外钙离子浓度的升高或降低可平行增加或减少钙电流和同时测量的EPPS。Ca~(2+)通道阻断剂(Cd~(2+)，500μM；ω-芋螺毒素，3μM)既可消除EPPS，又可消除神经外周电流中的Ca~(2+)成分。刺激ACh释放的NaF(10 MM)引起EPPS和神经周围钙电流的平行增加。腺苷A1受体激动剂NG-环己基腺苷(CHA)可抑制ACh的释放，但不影响神经外周电流。结果提示，在钙电流林格区同时记录钙电流和ACh释放是一种可靠的实验方法，可用于确定药物或疾病状态是否通过作用于突触前膜上的钙通道而影响ACh的释放。
Ca2+currents from the perineural region of motor nerve endings were measured together with evoked acetylcholine (ACh) release (i.e., end-plate potentials EPPs) in frog skeletal muscle in an attempt to define experimental conditions in which simultaneous measurements of both phenomena were feasible. In a solution containing low Ca2+(0.9 mM), high Mg2+(10 mM) and modest concentrations of K+channel blockers (250 μM tetraethylammonium, 100 μM 3,4,-diaminopyridine), reliable measurements of perineural Ca2+currents were possible. For convenience, this solution will be termed ‘Ca2+current’ Ringer. The mean number of ACh quanta released in Ca2+current Ringer was near the midpoint of the relationship between extracellular [Ca2+] and evoked ACh release observed previously in normal Ringer solutions. Consequently, ACh release in response to low-frequency motor nerve stimulation (0.05 Hz) was well maintained, allowing simultaneous measurements of Ca2+currents and evoked ACh release to be made. Ca2+currents and EPPs measured simultaneously in Ca2+current Ringer were increased or decreased in parallel by increasing or decreasing the extracellular Ca2+concentrations. Ca2+channel blockers (Cd2+, 500 μM; ω-conotoxin, 3 μM) eliminated both EPPs and the Ca2+component of the perineural current. NaF (10 mM), which stimulates ACh release, produced parallel increases in EPPs and perineural Ca2+currents. NG-cyclohexyladenosine (CHA), an A1adenosine receptor agonist, inhibits ACh release without effects on perineural currents. The results suggest that the concurrent electrophysiological recording of Ca2+currents and ACh release in Ca2+current Ringer is a reliable experimental approach for determining whether drugs or disease states affect ACh release by acting on Ca2+channels in the presynaptic membrane.