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Effect of hydroxylamine on photon‐like events during dark adaptation in toad rod photoreceptors
Author(s) -
Leibrock C.S.,
Lamb T.D.
Publication year - 1997
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1111/j.1469-7793.1997.00097.x
Subject(s) - hydroxylamine , bleach , rhodopsin , chemistry , biophysics , toad , photochemistry , biochemistry , biology , retinal , organic chemistry , ecology
1 The suction pipette technique was used to investigate the recovery of toad rod photoreceptors following small bleaches of 0.2‐3% of the rhodopsin. 2 The reduction in sensitivity and the increase in noise elicited by bleaches were measured, and from these measurements the underlying rate of occurrence of photon‐like events was calculated as a function of time after the bleach. 3 Exposure to hydroxylamine solution was used to hasten the decomposition of the meta‐rhodopsin photoproducts. The outer segment was exposed to 110 m m hydroxylamine in a low‐Ca 2+ Ringer solution for a period of 10–50 s beginning 10–17 min after the bleaching exposure. 4 By the time of the hydroxylamine exposure, the flash sensitivity and response kinetics had returned almost to normal, and were not significantly altered by the exposure. 5 Following hydroxylamine exposure, the rate of spontaneous photon‐like events in the rods declined rapidly to near pre‐bleach levels. 6 We conclude that hydroxylamine reduces the rate of occurrence of photon‐like events induced by a bleach, and we postulate that this reduction results from the removal of metarhodopsin (most likely metarhodopsin II) from the outer segment. 7 Our results are consistent with a model in which photon‐like events result from reversal of the reactions (phosphorylation and capping by arrestin) that lead to inactivation of the activated form of rhodopsin, Rh*.