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

K. Donner, S. Hemilä, Ari Koskelainen

Research output: Contribution to journalArticleScientificpeer-review


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. 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. The fast effects, including the leakage current, are attributable in part to direct action on the sodium channels in the plasma membrane.
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. Typically, the reagents also induced large ERG transients of non-receptor (glial) origin.
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.
Original languageEnglish
Pages (from-to)125-132
Publication statusPublished - 1989
MoE publication typeA1 Journal article-refereed


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