[Pharmacological sensitivity of the photopic c-wave in the electroretinogram of the chicken. I. Effects of sodium azide, adrenaline, and a barbiturate].

The c-wave recorded in the chicken electroretinogram proved to be cone-triggered. The effect of various drugs active on pigment epithelium and on c-waves in scotopic retinas were tested in order to determine whether a similar mechanism may underlie both rod- and cone-triggered c-waves. Our results indeed point to such a similar reactivity of both types of c-waves. Pentothal, a short-acting barbiturate induced--as it does in the sheep--a transient disappearance of the c-wave. Sodium azide and adrenaline produced very similar effects: when injected i.v., these drugs produced a transient increase in the resting potential of the eye (the "azide potential"). When injected im or i.p., both drugs provoked--as they do in rabbit or in rat retinas--an increase in the voltage of the c-wave, but this increase was preceded in the chicken by a partial or total suppression of this component.