A COMPARATIVE STUDY OF THE ACTION OF 8-Br-cGMP AND cGMP ON THE LIGHT-SENSITIVE CHANNEL IN TOAD RODS
8-Br-cGMP和cGMP对蟾蜍视杆光敏感通道作用的比较研究

Patch-clamp recordings were made from rod outer segments (ROS) of toad retina. 8-Br-cGMP opened a channel that appeared to be the same as light-sensitive channel, which was opened by cGMP from the same patch. Under the same patch membrane potential, 8-Br-cGMP also caused membrane current to increase to about the same magnitude from the same patch as did cGMP. However, the 8-Br-cGMP concentration was much lower than the cGMP concentration. Moreover, the rate which 8-Br-cGMP was hydrolyzed by phosphodiesterase is much more slowly than that cGMP did. The results suggest that 3', 5'-cyclic monophoshate of cGMP molecule plays an important role in opening the light-sensitive channel of ROS.