CEILING OF STIMULUS INDUCED RISES IN EXTRACELLULAR POTASSIUM CONCENTRATION IN CEREBRAL-CORTEX OF CAT
CEILING OF STIMULUS INDUCED RISES IN EXTRACELLULAR POTASSIUM CONCENTRATION IN CEREBRAL-CORTEX OF CAT
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DOI：
10.1016/0006-8993(77)90903-9
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发表时间：
1977-01-01
期刊：
影响因子：
2.9
通讯作者：
LUX, HD
中科院分区：
文献类型：
--
作者：
HEINEMANN, U;LUX, HD
在重复电刺激过程中，细胞外K+活性（aK）的水平测定与离子敏感微电极在猫的躯体感觉皮层，以确定在不同的实验条件下的最大值（上限水平）。在刺激皮层表面（CS）或丘脑腹后外侧核（VPL）和自我持续后放电（SAD）期间，aK的最大值为10.2毫微克/升。同样，前腹外侧核的峰值为6.5 meq/l，正中核和楔状核的峰值为4 meq/l。在测试刺激与恒定的强度和频率的aK的上升呈负相关的前一个刺激产生的aK的水平。此外，在SAD期间，当从aK的增强水平开始时，aK的上升较小。在CS或VPL的重复刺激期间，当通过用富含K+的溶液灌注将aK增加到10 meq/l以上的水平时，未观察到aK的升高。当在刺激诱导的aK水平增加期间应用时，神经诱发的K+测试信号降低10-48%。刺激诱导的K+变化可以成为负时，aK增加到7 meq/l以上的水平，通过局部电泳，而刺激诱导的神经元放电率的增加并没有消失或逆转。在刺激或灌流期间，ECoG [皮层电图]和局部诱发电位的振幅随着aK的增加而降低。在其稳定状态的上限显然是由一个积极的K+吸收机制，平衡额外的K+释放。此外，在aK水平升高时K+释放减少可能会限制aK的升高。
Levels of extracellular K+ activity (aK) during repetitive electrical stimulation were measured with ion sensitive microelectrodes in the somatosensory cortex of the cat to determine maximum values (ceiling levels) under different experimental conditions. The maximal values of aK were 10.2 meq/l during stimulation of the cortical surface (CS) or of the nucleus ventroposterolateralis thalami (VPL) and during self-sustained afterdischarges (SAD). Similarly, peak values were 6.5 meq/l for the nucleus ventrolateralis anterior and 4 meq/l for the nucleus centromedianus and for the nucleus cuneatus. The rise in aK during a test stimulus with constant intensity and frequency was inversely related to the level of aK produced by a preceding stimulation. Also the rise in aK during SAD was smaller when it started from an enhanced level of aK. During repetitive stimulation of CS or VPL a rise in aK was not observed when aK was increased to levels above 10 meq/l by superfusion with K+ enriched solutions. An electrophoretically evoked K+ test signal was reduced between 10-48% when applied during stimulus induced increased levels of aK. Stimulus induced K+ changes could become negative when aK was increased to levels above 7 meq/l by local electrophoresis, while the stimulus induced increase in neuronal discharge rate did not disappear or reverse. Amplitudes of ECoG [electrocorticogram] and local evoked potentials were reduced as aK increased during stimulation or superfusion. The ceiling in its steady state is apparently maintained by an active K+ uptake mechanism which balances extra releases of K+. Decreased release of K+ at increased levels of aK may in addition limit the rise in aK.