Leibrock C S, Reuter T, Lamb T D
Physiological Laboratory, University of Cambridge, England, UK.
Vision Res. 1994 Nov;34(21):2787-800. doi: 10.1016/0042-6989(94)90048-5.
The recovery of toad rod photoreceptors, following exposure to intense lights that bleached 0.02-3% of the rhodopsin, has been investigated using the suction pipette technique. The post-bleach period was accompanied by reduced flash sensitivity, accelerated kinetics, and spontaneous fluctuations (noise). The power spectrum of the fluctuations had substantially the form expected for the random occurrence of single-photon events, and the noise could therefore be expressed as a "photon-noise equivalent intensity". From the level of desensitization at any time, the after-effect of the bleach could also be expressed in terms of a "desensitization-equivalent intensity", and this was found to be at least a factor of 20 times higher than the noise-equivalent intensity at the corresponding time. Our results indicate that a bleach induces two closely-related phenomena: (a) a process indistinguishable from the effect of real light, and (b) another process which desensitizes and accelerates the response in the same way that light does, but without causing photon-like noise. We propose a mechanism underlying these processes.
利用吸管技术，研究了蟾蜍视杆光感受器在暴露于使0.02%-3%的视紫红质漂白的强光后的恢复情况。漂白后的时期伴随着闪光敏感度降低、动力学加速和自发波动（噪声）。波动的功率谱基本上具有单光子事件随机发生时预期的形式，因此噪声可以表示为“光子噪声等效强度”。从任何时刻的脱敏水平来看，漂白的后效应也可以用“脱敏等效强度”来表示，并且发现这至少比相应时间的噪声等效强度高20倍。我们的结果表明，漂白会引发两种密切相关的现象：(a) 一种与真实光的效应无法区分的过程，以及 (b) 另一种过程，它以与光相同的方式使反应脱敏并加速，但不会产生类似光子的噪声。我们提出了这些过程背后的一种机制。
