Single-channel recordings demonstrate that cGMP opens the light-sensitive ion channel of the rod photoreceptor.
Single-channel recordings demonstrate that cGMP opens the light-sensitive ion channel of the rod photoreceptor.
复制标题
单通道记录表明 cGMP 打开视杆光感受器的光敏离子通道。
DOI：
10.1073/pnas.84.1.299
复制
发表时间：
1987
影响因子：
11.1
通讯作者：
Matthews,G
中科院分区：
文献类型：
--
作者：
Matthews,G
用膜片钳技术对蟾蜍视网膜单个暗适应视杆细胞外节进行记录。当贴片移液器充满了解决方案，不含二价阳离子，内向电流通过个别光敏离子通道是足够大，允许单通道记录。通道活动被抑制的黑暗适应杆的正常响应范围内的照明。当照明被限制在外部段的一部分时，光对通道活性的影响在空间上局限于照明区域。记录的补丁的超极化没有减少通道开放的频率，这表明抑制通道活动的光是由于照明本身，而不是光诱导的超极化杆。在记录完整细胞中的单个光敏通道活动后，将膜的贴片分离以形成切除的由内而外的贴片。将环GMP应用于切下的贴片的细胞内面，然后打开一个通道，该通道似乎与之前在完整的功能性杆中从相同膜记录的光敏通道相同。这提供了直接的证据表明，环GMP作为一种内部递质，打开了脊椎动物感光器的光敏通道。
Patch-clamp recordings were made from outer segments of single dark-adapted rod photoreceptors from toad retina. When patch pipettes were filled with a solution free of divalent cations, inward current through individual light-sensitive ion channels was sufficiently large to allow single-channel recording. Channel activity was suppressed by illumination within the normal response range of the dark-adapted rod. When illumination was restricted to a portion of the outer segment, the effect of light on channel activity was spatially localized to the illuminated region. Hyperpolarization of the recorded patch did not reduce the frequency of channel opening, indicating that the suppression of channel activity by light was due to illumination itself and not to light-induced hyperpolarization of the rod. After recording single light-sensitive channel activity in the intact cell, the patch of membrane was detached to form an excised, inside-out patch. Cyclic GMP applied to the intracellular face of the excised patch then opened a channel that appeared to be the same as the light-sensitive channel recorded earlier from the same membrane in the intact, functioning rod. This provides direct evidence that cyclic GMP acts as an internal transmitter that opens the light-sensitive channel of the vertebrate photoreceptor.