Figure 2.

The effect of 11-cis 9-demethyl retinal (9-DM) on the time course of flash response recovery after a bleach. (A) Current recordings were made from the same red cone under three different conditions: the cell contained native dark-adapted pigment (top), the cell contained 11-cis 9-demethyl pigment (middle), and the cell contained 11-cis retinal pigment (bottom). In each recording, the cell was exposed to a 4-s step of 620-nm light that bleached in excess of 90% of the visual pigment. Recovery of responsiveness was monitored by exposure to 20-ms saturating test flashes at 10-s intervals (see light monitor). (B) Time course of the recovery of photocurrent (increasing amplitude plotted downward) as determined from the responses shown in A. Solid lines indicate data fitted with a single exponential function. The experiment was performed on a total of nine cells with similar results; mean time constants are presented in Table I.