首页 | 本学科首页   官方微博 | 高级检索  
     检索      


Measurement of the intracellular free calcium concentration in salamander rods
Authors:McNaughton P A  Cervetto L  Nunn B J
Abstract:Measurement of the free calcium concentration within a photo-receptor outer segment has been considered an important aim since the proposal by Hagins and Yoshikami that the primary event in phototransduction is a release of Ca (2+) inside the cell. More recent evidence has cast doubt on the calcium hypothesis, and the observations of Yau and Nakatani and Matthews et al. suggest that the internal Ca (2+) concentration (Ca (2+)]i), may decrease after a flash of light. In the present study we have measured Ca (2+)]i directly by using a new method for incorporating the Ca-sensitive photoprotein aequorin into an isolated rod. We report that the light response is accompanied by a decrease in Ca (2+)]i, caused by the closure of light-sensitive channels which are the main route for Ca (2+) entry into the outer segment. Of the Ca (2+) entering through light-sensitive channels, about 95% is sequestered by a rapid and reversible buffering mechanism. Calcium is removed from the cell by an electrogenic pump in which 3 Na (+) ions are exchanged for each Ca (2+); the pump is highly active and the free Ca (2+) in the cell declines with a time constant of ~0.5 s after a flash of light.
Keywords:
本文献已被 PubMed 等数据库收录!
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号