Carrasquer G, Yang S, Schwartz M, Dinno M A
Department of Medicine (Nephrology), University of Louisville, Kentucky 40292, USA.
Proc Soc Exp Biol Med. 1996 Feb;211(2):205-9. doi: 10.3181/00379727-211-43963.
The effect of melittin on electrophysiological parameters of the bullfrog cornea was studied using an in vitro preparation. Epithelial cells of corneas were impaled with microelectrodes. Experiments were done under short-circuit current (Isc) conditions. Melittin was added in concentrations of 10(-5)M to the stromal or 10(-6)M to the tear solution. The effects of melittin were as follows: (i) stromal side, a decrease in Isc; an increase in the apical membrane fractional resistance, fRo; no change in the transepithelial conductance, gt; and a depolarization of the intracellular potential, Vo; (ii) tear side, an initial (first 10 min) increase and then a decrease in Isc; a decrease in fRo; an initial (first 10 min) increase with subsequent small decrease in gt; and a depolarization of Vo. Changes in tear Na+, but not in tear K+, with melittin present in tear solution, induced changes in some electrical parameters. The effects on the tear side may be explained by opening of nonspecific channels in the apical membrane with some specificity for Na+ channel. The subsequent effects on the tear and the effects on the stromal side may be explained by an inhibition of the primary transport system, that is, of the Na+/K+ -ATPase pump located in the basolateral membrane. In these experiments, there was no evidence of opening of channels in the basolateral membrane.
采用体外制备方法研究了蜂毒肽对牛蛙角膜电生理参数的影响。用微电极刺入角膜上皮细胞。实验在短路电流（Isc）条件下进行。将浓度为10（-5）M的蜂毒肽添加到基质中，或将浓度为10（-6）M的蜂毒肽添加到泪液中。蜂毒肽的作用如下：（i）基质侧，Isc降低；顶端膜分数电阻fRo增加；跨上皮电导gt无变化；细胞内电位Vo去极化；（ii）泪液侧，Isc最初（前10分钟）增加，然后降低；fRo降低；gt最初（前10分钟）增加，随后略有降低；Vo去极化。泪液中存在蜂毒肽时，泪液Na+发生变化，而泪液K+未发生变化，这引起了一些电参数的变化。对泪液侧的影响可能是由于顶端膜中非特异性通道的开放，这些通道对Na+通道具有一定特异性。随后对泪液侧的影响以及对基质侧的影响可能是由于初级转运系统受到抑制，即位于基底外侧膜的Na+/K+-ATP酶泵受到抑制。在这些实验中，没有证据表明基底外侧膜中的通道开放。
