Effect of N-Ethyl maleimide on the delay of onset of the ERG a-wave after light adaptation

Abstract

The delay in the onset of the ERG a-wave that occurs during the recovery from light adaptation is decreased when N-ethyl maleimide, (NEN), (a sulfhydryl reactor) dissolved in saline solution is injected into the vitreous humor immediately after the adapting light is turned off. Control experiments show that injection of NEM into the dark adapted eye had very little effect on the a-wave. Repositioning the eye and electrode, insertion of an empty needle, or injection of saline solusion into the eye after light adaptation did not affect the delay of onset of the a-wave. It is suggested therefore that the opsin-based sulfhydryl group liberated in the light reaction serves as an inhibitor of the reactions leading to the generation of the a-wave.