Failure to reverse the photocurrent in standard ionic conditions. (A) A Hesse cell was voltage clamped at −50 mV, and depolarizing steps of 2.5-s duration were applied every 60 s, increasing the amplitude at 10-mV increments. At 800 ms after the onset of the voltage stimulus, a 100-ms light flash of constant intensity was delivered (3.8 × 10¹² photons/cm²). Photocurrent size decreased with depolarization but did not reverse polarity, even after stepping membrane voltage up to +100 mV. (B) Peak photocurrent amplitude plotted as a function of membrane voltage, revealing a pronounced inward rectification of the I-V relation.