Syková E
Can J Physiol Pharmacol. 1987 May;65(5):1058-66. doi: 10.1139/y87-167.
The neuronal activity in spinal cord in response to electrical or adequate stimulation of afferent fibres increases extracellular K+ activity. The increase during a stimulation can reach 9-10 mM (so-called ceiling level) and persists for some time even when a stimulation is discontinued. The activation of a neuronal Na-K pump is a limiting factor in stimulation-evoked increase in extracellular K+ activity and in the time course of its recovery to the resting level. Drugs that affect either the neuronal activity (picrotoxin, strychnine, GABA, 5-HT) or activity of Na-K ATPase (oubain, naloxone, morphine, enkephalins) substantially change the K+ transience. Repetitive electrical stimulation of low threshold cutaneous afferents at frequency 1-100 Hz induced transient shrinkage of extracellular space in spinal dorsal horns by 5-75%. The increase in extracellular K+ activity depolarizes the membranes of neurones, glial cells, and primary afferent fibres and may eventually lead to either facilitation or inhibition of synaptic transmission. It is also suggested that the transient poststimulation changes in extracellular volume may alter synaptic potency in spinal cord.
脊髓中神经元活动对传入纤维的电刺激或适宜刺激产生反应，会使细胞外钾离子活性增加。刺激过程中钾离子活性的增加可达9 - 10 mM（所谓的上限水平），并且即使刺激停止后仍会持续一段时间。神经元钠钾泵的激活是刺激诱发的细胞外钾离子活性增加及其恢复到静息水平的时间进程中的一个限制因素。影响神经元活动（印防己毒素、士的宁、γ-氨基丁酸、5-羟色胺）或钠钾ATP酶活性（哇巴因、纳洛酮、吗啡、脑啡肽）的药物会显著改变钾离子的瞬变情况。以1 - 100 Hz的频率重复电刺激低阈值皮肤传入纤维，可使脊髓背角的细胞外间隙瞬间缩小5 - 75%。细胞外钾离子活性的增加会使神经元、神经胶质细胞和初级传入纤维的膜去极化，并最终可能导致突触传递的易化或抑制。也有人认为，刺激后细胞外体积的短暂变化可能会改变脊髓中的突触效能。
