非洲爪蟾视网膜中视杆光感受器对视紫红质、视紫质和视紫蓝质的形成、转化及利用

Formation, conversion, and utilization of isorhodopsin, rhodopsin, and porphyropsin by rod photoreceptors in the Xenopus retina.

作者信息

Witkovsky P, Engbretson G A, Ripps H

出版信息

J Gen Physiol. 1978 Dec;72(6):821-36. doi: 10.1085/jgp.72.6.821.

DOI:10.1085/jgp.72.6.821

PMID:731199

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC2228495/

Abstract

The visual pigment content of rod photoreceptors in Xenopus larvae was reduced greater than 90% through a combination of vitamin A-deficient diet and constant light. Thereafter, a dose of either all-trans-retinol or 9-cis-retinal was injected intramuscularly, leading to the formation of a rhodopsin (lambdamax 504 nm) or isorhodopsin (lambdamax 487-493 nm) pigment, respectively. Electrophysiological measurements were made of the threshold and spectral sensitivity of the aspartate-isolated PIII (photoreceptoral) component of the electroretinogram. These measures established that either rhodopsin or isorhodopsin subserved visual transduction with the same efficiency as the 519 nm porphyropsin pigment encountered normally. When animals with rhodopsin or isorhodopsin were kept in darkness or placed on a cyclical lighting regimen for 8 days, retinal densitometry showed that either pigment was being converted to porphyropsin; significantly more porphyropsin was formed as a result of cyclical lighting than after complete darkness.

摘要

通过缺乏维生素A的饮食和持续光照相结合的方式，非洲爪蟾幼体杆状光感受器中的视觉色素含量降低了90%以上。此后，分别肌肉注射一剂全反式视黄醇或9-顺式视黄醛，导致分别形成视紫红质（最大吸收波长504 nm）或异视紫红质（最大吸收波长487 - 493 nm）色素。对视网膜电图中天冬氨酸分离的PIII（光感受器）成分的阈值和光谱敏感性进行了电生理测量。这些测量结果表明，视紫红质或异视紫红质在视觉转导中的作用效率与正常情况下遇到的519 nm视紫蓝质色素相同。当含有视紫红质或异视紫红质的动物处于黑暗中或接受8天的周期性光照方案时，视网膜密度测定显示，两种色素都在转化为视紫蓝质；与完全黑暗后相比，周期性光照导致形成的视紫蓝质明显更多。