PROLONGED DEPOLARIZING AFTERPOTENTIAL AND ITS CONTRIBUTION TO UNDERSTANDING OF PHOTORECEPTOR FUNCTION
PROLONGED DEPOLARIZING AFTERPOTENTIAL AND ITS CONTRIBUTION TO UNDERSTANDING OF PHOTORECEPTOR FUNCTION
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DOI：
10.1007/bf00535813
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发表时间：
1977-01-01
期刊：
影响因子：
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通讯作者：
RAZMJOO, S
中科院分区：
文献类型：
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作者：
HAMDORF, K;RAZMJOO, S
比较维生素A-贫和维生素A-富饲料饲养的苍蝇显示，后者表现出，蓝色照明后，1）轻微偏离刺激强度和受体敏感性之间的线性关系，2）强烈的蓝色照明后的PDA的现象。这两种效应都可能是由于这种膜中的色素距离减少所致。在用蓝光照射约20秒后产生最大PDA，并且在此之后，观察到膜的电阻保持较低，以与PDA下降相同的速率返回到静息值。对测试闪光的反应在照明过程中被抑制，在PDA下降期间逐渐恢复，类似于感光器对两种刺激的总和的反应：测试闪光和背景照明的减少。蓝光后立即红光消除PDA，白色光产生小PDA。所有这些实验都证实了一个新的模型（不诉诸抑制剂的概念），其将色素与受体兴奋联系起来，其假设如下：1）PDA是在视紫红质分子的异常高的初级量子吸收之后产生的，2）PDA是被储存形式的物质延迟的膜激发，3）当这种物质的生产大于其消耗时，储存被建立; 4）时间和能量对于兴奋性视紫红质分子的再生是必要的。
Comparison of flies bred on vitamine A-poor and vitamine A-rich diets show the latter to exhibit, after blue illumination, 1) slight deviation from the linear relationship between stimulus intensity and receptor sensitivity and, 2) after intense blue illumination the phenomenon of the PDA. Both these effects could result from reduced pigment distances in such membranes. Maximum PDA was produced after about 20 s of illumination with blue light, and following this the resistance of the membrane was seen to stay low, returning to the resting value at the same rate as the PDA decline. The response to test flashes, repressed during illumination, gradually returned during the decline of the PDA, similar to the way the photoreceptor would respond to the sum of two stimuli: the test flash and a decreasing background illumination. Red light immediately following blue abolished the PDA and white light produced a small PDA. All these experiments corroborate a new model (without resorting to the concept of inhibitors) which links the photopigments with receptor excitation, the assumptions for which are the following: 1) PDA is produced after abnormally high primary quantum absorption by rhodopsin molecules, 2) PDA is a retarded membrane excitation by a substance in stored form, 3) the store is built up when production of this substance is larger than its consumption, and 4) time and energy are necessary for the regeneration ofexcitatoryrhodopsin molecules.