Changes in sodium activity during light stimulation in photoreceptors, glia and extracellular space in drone retina.
Changes in sodium activity during light stimulation in photoreceptors, glia and extracellular space in drone retina.
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无人机视网膜光感受器、神经胶质细胞和细胞外空间受光刺激时钠活性的变化。
DOI：
10.1113/jphysiol.1985.sp015686
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发表时间：
1985
期刊：
影响因子：
--
通讯作者：
Orkand,RK
中科院分区：
文献类型：
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作者：
Coles,JA;Orkand,RK
使用离子选择性微电极测量两种类型细胞（光感受器和神经胶质细胞）以及蜜蜂雄蜂（蜜蜂雄性）视网膜灌流切片细胞外间隙中的Na+活性aNa。光刺激或增加灌流液中的[K+]可诱导Na+的运动。在黑暗中，光感受器中的aNa为IOmM（S.E.平均值= 1 mM）;在神经胶质细胞中更高：37 +/-2 mM。我们估计，在该制备物中，组织中约2/3的游离Na+在神经胶质细胞中。以1 s-1持续90 s的一系列闪光刺激，导致光感受器中的aNa增加16 +/-2 mM。K+活性aK降低21 +/-3 mM。在标准系列闪光期间，神经胶质细胞中的aNa仅降低1.5 +/-0.3 mM，远低于aK的增加（7 +/-2 mM）。对这一结果的一种可能解释是，aK的大部分增加是由于Na+-K+交换以外的机制引起的K+吸收。在细胞外液中，刺激导致aNa在约10 s内下降到相对稳定的值。与aK不同，在90 s刺激的剩余时间内，aNa没有返回基线的趋势。aNa的下降为14 +/-1 mM：细胞外电流和细胞外体积的减少阻止了更大的下降。当灌流液中的[K+]从7.5 mM增加到18 mM时，神经胶质细胞中的aNa降低，但光感受器中的aNa不降低。在这种组织中，刺激引起神经元中aNa的变化，这种变化可能大到足以改变细胞的生物化学。但在神经胶质中，分数变化很小。
Ion‐selective micro‐electrodes were used to measure Na+ activity, aNa, in the two types of cell, photoreceptors and glial cells, and in the extracellular space, in superfused slices of the retina of the honey‐bee drone, Apis mellifera male. Movements of Na+ were induced by light stimulation, or by increasing [K+] in the superfusate. In the dark, aNa in the photoreceptors was 10 mM (S.E. of the mean = 1 mM); in the glial cells it was higher: 37 +/‐ 2 mM. We estimate that in this preparation about 2/3 of the free Na+ in the tissue is in the glial cells. Stimulation with a train of light flashes, 1 s‐1 for 90 s caused aNa in the photoreceptors to increase by 16 +/‐ 2 mM. K+ activity, aK, decreased by 21 +/‐ 3 mM. During the standard train of light flashes, aNa in glial cells decreased by only 1.5 +/‐ 0.3 mM, much less than the increase in aK (7 +/‐ 2 mM). One possible interpretation of this result is that most of the increase in aK is due to K+ uptake by a mechanism other than Na+‐K+ exchange. In extracellular fluid, stimulation caused aNa to fall to a relatively steady value in about 10 s. Unlike aK, there was no tendency for aNa to return to the base line during the remainder of the 90 s stimulation. The fall in aNa was 14 +/‐ 1 mM: a greater fall is prevented by extracellular electric currents and a decrease in extracellular volume. When [K+] in the superfusate was increased from 7.5 to 18 mM, aNa decreased in the glial cells but not in the photoreceptors. In this tissue, stimulation causes changes in aNa in the neurones that might be large enough to modify the biochemistry of the cells. But in the glia, the fractional changes are small.