Figure 1.

Sample recordings of the dark current of a toad rod in normal and forskolin-containing Ringer. (A) SPRs in normal Ringer (black curve) and Ringer with 2 mM forskolin (red curve) derived from statistics of 40 responses to weak (mean 2.2 R*) flashes. Circles with error bars show discrete dark events that were cut off continuous records, aligned along time axis and averaged. Each point is the mean of 15 events ± SEM. (B) Long-lasting continuous record of the rod in complete darkness, in normal Ringer (black trace) and in forskolin-containing solution (red trace). Recordings were digitally low-pass filtered at 3 Hz (8-pole Bessel filter) and corrected for slow irregularities of the base line (Appendix, Fig. 10). Dark current was 24.4 pA and did not change more than ±0.5 pA during the recording.