Prolonged time course of glutamate release from nerve terminals: relationship between stimulus duration and the secretory event.
Prolonged time course of glutamate release from nerve terminals: relationship between stimulus duration and the secretory event.
复制标题
神经末梢谷氨酸释放的延长时间过程：刺激持续时间与分泌事件之间的关系。
DOI：
10.1046/j.1471-4159.1995.64052022.x
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发表时间：
1995
影响因子：
4.7
通讯作者：
Dunlap,K
中科院分区：
文献类型：
--
作者：
Turner,TJ;Dunlap,K
突触体[3H]谷氨酸释放的动力学进行了测量，在亚秒级的时间尺度上，以研究之间的关系，去极化的长度和分泌事件的持续时间。由升高的K+诱发的释放的时间过程是复杂的，在200 ms去极化后持续几秒钟。我们开发了一种在毫秒时间尺度上去极化可兴奋膜的方案，通过使用蛙毒素激活Na+通道来提供短暂的去极化，称为合成动作电位。通过用含有高浓度Na+的溶液进行灌流来实现去极化，并且通过在灌流溶液中包括河豚毒素（TTX）以阻断Na+进入来限制去极化的持续时间。使用膜片钳记录方法在蛙毒素处理的感觉神经元中直接测量Na+电流和膜去极化的时程。Na+和TTX浓度的快速增加产生瞬时增加内向Na+电流衰减与TTX浓度成正比的时间过程。电流钳测量表明，10 µMTTX的去极化持续时间为1.30 ms。尽管如此，由合成动作电位触发的[3H]谷氨酸的突触体释放仍然延长。某些突触的短暂神经元动作电位可能会触发持续数秒的递质释放。
The kinetics of synaptosomal [3H]glutamate release were measured on a subsecond time scale to study the relationship between the length of depolarization and the duration of the secretory event. The time course of release evoked by elevated K+was complex, proceeding for several seconds after a 200‐ms depolarization. We developed a protocol for depolarizing excitable membranes on a millisecond time scale to deliver brief depolarizations, termed the synthetic action potential, by using batrachotoxin to activate Na+channels. Depolarization is achieved by superfusing with solutions containing elevated concentrations of Na+, and the duration of the depolarization is limited by including tetrodotoxin (TTX) in the superfusion solution to block Na+entry. Direct measurements of the time courses of Na+current and membrane depolarizations were made in batrachotoxin‐treated sensory neurons using patch clamp recording methods. Rapid increases in Na+and TTX concentrations produced transient increases in inward Na+current that decayed with a time course proportional to TTX concentration. Current clamp measurements indicated that, with 10 µMTTX, depolarizations last ∼30 ms. Nonetheless, synaptosomal release of [3H]glutamate triggered by the synthetic action potential remained prolonged. Brief neuronal action potentials at some synapses may trigger transmitter release that persists for several seconds.