Gray-Keller M P, Detwiler P B
Department of Physiology and Biophysics, University of Washington School of Medicine, Seattle 98195, USA.
Neuron. 1996 Aug;17(2):323-31. doi: 10.1016/s0896-6273(00)80163-4.
Light adaptation is thought to be orchestrated by a Ca2+ feedback signal that desensitizes the response by speeding recovery. To evaluate the role of Ca2+ in adaptation, we compared the effect of lowered Ca2+ on response properties in darkness and during adaptation. Internal Ca2+ was reduced from its normal resting dark level (535 nM) by either background illumination or exposure to Ringer's solution containing low Ca2+ and/or cyclic GMP-gated channel blockers in darkness. Ca2+ reductions in light decreased the activation gain of the transduction process and speeded recovery kinetics, while equivalent Ca2+ reductions in darkness caused similar gain reduction without accelerating recovery. This indicates that adaptational changes in the response are not due purely to feedback effects on recovery.
光适应被认为是由一种Ca2+反馈信号精心调控的，该信号通过加速恢复来使反应脱敏。为了评估Ca2+在适应过程中的作用，我们比较了降低Ca2+对黑暗中和适应过程中反应特性的影响。在黑暗中，通过背景光照或暴露于含有低Ca2+和/或环鸟苷酸门控通道阻滞剂的林格氏液中，使内部Ca2+从其正常的静息黑暗水平（535 nM）降低。光照下Ca2+的减少降低了转导过程的激活增益并加快了恢复动力学，而黑暗中同等程度的Ca2+减少导致类似的增益降低，但没有加速恢复。这表明反应中的适应性变化并非纯粹归因于对恢复的反馈效应。
