McNaughton P A, Yau K W, Lamb T D
Nature. 1980 Jan 3;283(5742):85-7. doi: 10.1038/283085a0.
Visual transduction in vertebrate photoreceptors is thought to involve a diffusible internal transmitter which links photon absorption in disk membranes to the conductance decrease in the plasma membrane of the outer segment. The desensitisation of the photoresponse which occurs during and after illumination may also involve a diffusible substance, because a photon absorbed in one disk can desensitise the cell's response to a subsequent photon absorbed in a different disk. Although both activation and desensitisation spread longitudinally from the site of photon absorption, neither spreads over the entire length of the outer segment. We report here experiments which indicate that, with dim illumination, both effects decline to be half-maximal in less than 8 micrometers from the site of light absorption.
脊椎动物光感受器中的视觉转导被认为涉及一种可扩散的内部递质，它将盘膜中的光子吸收与外段质膜中的电导降低联系起来。光照期间和之后发生的光反应脱敏也可能涉及一种可扩散物质，因为在一个盘中吸收的光子可以使细胞对在另一个盘中吸收的后续光子的反应脱敏。尽管激活和脱敏都从光子吸收部位纵向扩散，但两者都不会扩散到外段的整个长度。我们在此报告的实验表明，在弱光照射下，两种效应在距光吸收部位不到8微米的距离内下降至最大值的一半。
