Positive and Negative Potential Responses associated with Vertebrate Photoreceptor Cells

Abstract

IN a previous paper it was shown, by means of an electrophoretic staining technique, that negative d.c. potentials, similar to the S potentials of fish retinae, can be recorded from, the inner segments of photoreceptor cells during retinal illumination¹. These responses were referred to as photoreceptor potentials. The present communication describes positive potential responses which appear to be associated with the negative d.c. potentials and which may also represent the activity of photoreceptor cells. The experimental animal used in these investigations was the common mud puppy, Necturus maculosus. The recording micro-electrodes were usually filled with 3 M potassium chloride, although a few contained a saturated aqueous solution of trypan blue which could be electrophoretically deposited in the impaled structure after recording its light-elicited response. In these experiments the eye remained in its orbit while the micro-electrode was introduced into the retina from the vitreous by means of a mechanical micromanipulator. More complete details of the experimental procedure are given elsewhere¹.