Light-induced changes in GTP and ATP in frog rod photoreceptors. Comparison with recovery of dark current and light sensitivity during dark adaptation.
Light-induced changes in GTP and ATP in frog rod photoreceptors. Comparison with recovery of dark current and light sensitivity during dark adaptation.
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DOI：
10.1085/jgp.85.1.107
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发表时间：
1985-01
期刊：
影响因子：
--
通讯作者：
Bownds MD
中科院分区：
文献类型：
--
作者：
Biernbaum MS;Bownds MD
光照降低了生理活性青蛙杆外节段仍附着在其内节椭球(OS-IS)上的纯化悬浮液中的GTP和ATP水平。(A)OS-IS(T1/2=40 S)的GTP下降较孤立外段(T1/2=7 S)慢，提示OS-IS存在更有效的缓冲作用。(B)只有在大于饱和光响应所需的强度时，才能检测到GTP的下降。当连续光的强度增加超过4个对数单位时，GTP水平随着对数强度的线性下降高达60%。在中等强度的延长光照期间，GTP被降低到稳定的中间水平。(C)当光照漂白水平超过视紫红质的0.003%时，可以检测到三磷酸腺苷水平的下降。(D)闪光后，GTP水平先降后升，恢复时间取决于闪光的强度。(E)在0.2%和2%闪光漂白后，GTP水平的恢复与光敏感度的恢复同步，光敏感度的恢复慢于暗电流的恢复。这增加了GTP水平与光敏感度之间存在联系的可能性。
Light decreases GTP and ATP levels in purified suspensions of physiologically active frog rod outer segments still attached to their inner segment ellipsoids (OS-IS). (a) The GTP decrease is slower in OS- IS (t1/2 = 40 s) than in isolated outer segments (t1/2 = 7 s), which suggests there is more effective buffering in OS-IS. (b) The GTP decrease becomes detectable only at intensities greater than those required to saturate the photoresponse. As the intensity of a continuous light is increased over 4 log units, GTP levels decrease linearly with log intensity by as much as 60%. GTP is reduced to steady intermediate levels during extended illumination of intermediate intensity. (c) At levels of illumination bleaching greater than 0.003% of the rhodopsin, a decrease in ATP levels becomes detectable. (d) Following a flash, GTP levels fall and then rise with a recovery time dependent on the intensity of the flash. (e) After both 0.2 and 2% flash bleaches, the recovery of GTP levels parallels the recovery of light sensitivity, which is slower than the recovery of the dark current. This raises the possibility of a link between GTP levels and light sensitivity.