Effects of sulfhydryl binding reagents on the photoresponses of amphibian retinal rods

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Comparative Biochemistry and Physiology. 1989. 94: 125-132.

Title: Effects of sulfhydryl binding reagents on the photoresponses of amphibian retinal rods
Author: Donner, K.; Hemilä, S.; Koskelainen, A.
Contributor organization: Department of Biological and Environmental Sciences
Bio- ja ympäristötieteiden laitos
Bio- och miljövetenskaper, Institutionen för
Publisher: Elsevier
Date: 1989
Language: eng
ISSN: 1095-6433
DOI: http://dx.doi.org/doi:10.1016/0300-9629(89)90795-0
URI: http://hdl.handle.net/1975/941
Abstract: 1. 1. We have studied the effects of four sulfhydryl binding reagents (NEM, PHMB, PCMP and IAA) and the disulfide reducing agent, DTT, on the photocurrent of vertebrate rods by recording the ERG across the aspartate-treated retina of the frog, and by suction pipette recording from isolated rods of the tiger salamander. 2. 2. SH-reagents brought about three types of effects on rods: (1) a fast transitory increase in light sensitivity and photocurrent; (2) a “leakage” current that could not be turned off by light; and (3) a slower irreversible loss of sensitivity. 3. 3. The fast effects, including the leakage current, are attributable in part to direct action on the sodium channels in the plasma membrane. 4. 4. NEM, PHMB and PCMP were able to affect the transduction machinery inside the rod, which first contributed to the growth of photoresponses, but gradually depressed light sensitivity irreversibly. 5. 5. Typically, the reagents also induced large ERG transients of non-receptor (glial) origin. 6. 6. The fast effects of DTT on isolated rods were similar to those of the SH-reagents. This drug) however, had no clear effect on ERG photoresponses, suggesting that the oxidation of sodium-channel SH-groups is modest in the intact retina as compared with isolated rods.

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