cGMP and EGTA increase the light-sensitive current of retinal rods.
cGMP and EGTA increase the light-sensitive current of retinal rods.
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cGMP 和 EGTA 增加视网膜杆的光敏电流。
DOI：
10.1016/0006-8993(83)91331-8
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发表时间：
1983
期刊：
影响因子：
2.9
通讯作者：
Lipton,SA
中科院分区：
文献类型：
--
作者：
Lipton,SA
光对视网膜的刺激会导致通常在黑暗中流入视杆外节的内向电流减少。 cGMP 和 Ca2+ 都被认为是内部信使，通过调节这种“光敏感”内向电流来介导对光照的反应和适应。由于多项证据表明 cGMP 和 Ca2+ 的水平会随着光刺激而变化，因此确定这些物质是否影响视杆细胞中的光敏电流很有意义。在本研究中，对单独培养的光感受器进行电压钳位并用TEA、Cs+和Co2+处理以隔离光敏电流。使用这种新方法，细胞内注射 cGMP 或 EGTA 会增加黑暗中的内向电流。随后对明亮闪光的反应更大，可能是因为有更多的光敏电流需要被抑制。随着这些物质注射时间的延长，需要越来越亮的闪光才能引起最大反应。由于 cGMP 或 EGTA 感应电流的反转电位与正常光敏电流相同，因此两种电流的离子基础看起来相同。 Ca2+ 或 cGMP 的变化可以调节光敏电流这一发现支持了两者都可能充当视杆外节的内部信使的观点。
Stimulation of the retina by light leads to a decrease in the inward current that normally flows into rod outer segments in the dark. Both cGMP and Ca2+have been proposed as internal messengers that mediate the response and adaptation to illumination by regulating this ‘light-sensitive’ inward current. Since several lines of evidence suggest that the levels of cGMP and Ca2+change with photostimulation, it was of interest to determine if these substances affect the light-sensitive current in rods. In the present study, solitary cultured photoreceptors were voltage-clamped and treated with TEA, Cs+and Co2+to isolate the light-sensitive current. Using this new method, intracellular injection of either cGMP or EGTA produced an increase in the inward current in the dark. Subsequent responses to bright flashes were larger, probably because there was more light-sensitive current to be suppressed. With longer injections of these substances, increasingly brighter flashes were necessary to elicit a maximum response. Since the reversal potential of the cGMP- or EGTA-induced current was the same as the normal light-sensitive current, the ionic basis of the two currents appeared identical. The finding that a change in Ca2+or cGMP can modulate the light-sensitive current supports the notion that both may act as internal messengers in rod outer segments.