Local effects of bleaching in retinal rods of the toad.
- 1 July 1982
- journal article
- research article
- Published by Wiley in The Journal of Physiology
- Vol. 328 (1), 49-71
- https://doi.org/10.1113/jphysiol.1982.sp014252
Abstract
Suction electrode recordings were used to study the recovery of responsiveness in single toad rods after bleaching a small fraction (> 5%) of the rhodopsin. After a spatially uniform bleach that initially abolished the dark current over the entire length of the outer segment, the more proximal regions recovered faster than the more distal regions. For a time the most basal region was almost fully recovered while the tip remained fully saturated. Such a gradient of responsiveness did not occur during uniform steady background illumination of dark-adapted cells. The entire outer segment recovered uniformly after a longitudinally graded bleach that simulated the pattern produced by self-screening in the intact eye. The recovery of the distal end of the outer segment was not affected by a bleach at the proximal end. Apparently, the differences in recovery rate reflect intrinsic local properties of the outer segment rather than longitudinal diffusion of a substance from the inner segment. For at least the first 3 min after bleaching with a narrow transverse slit the reduction of responsiveness remained most pronounced in the bleached region, suggesting that this effect of bleaching does not spread extensively. The increased noise induced by bleaching originates locally in the bleached region of outer segment. When the tip was locally saturated after a bleach or during steady light, the current recorded from the tip was predominantly capacitive, resulting from intracellular voltage change. Apparently, when the dark current is abolished the outer segment plasma membrane has negligible leakage conductance.This publication has 17 references indexed in Scilit:
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