Fig. 2.

PKC activators decrease the photoreceptor's sensitivity to light. A, The receptor potential, under current-clamp recording, decreases with increasing (−)-indolactam V concentrations. B, PDBu also decreases the receptor potential, whereas the inactive 4α-phorbol has no effect. Thehorizontalbarbelow thetrace represents the duration of the light flash (20 msec; log₁₀ −5.4). Compounds were dissolved in DMSO and applied extracellularly to the bath. The percent DMSO was 0.18% for the different concentrations of (−)-indolactam V, 0.2% for PDBu, and 0.1% for 4α-phorbol.