Prolonged aftereffects of intense illumination in Lima rhabdomeric photoreceptors. (A) Current clamp recording in a cell stimulated with a bright flash of light (5.4 × 10¹⁵ photons × cm⁻² × s⁻¹). After the complex-shaped receptor potential and a train of action potentials, membrane voltage drifted in the depolarizing direction by ≈15 mV. (B) Recordings in three different cells, shown at a more compressed time scale, to illustrate the prolonged time course of the after-depolarization. (C) A similar photostimulation applied to a different cell under whole cell voltage clamp, internally dialyzed with standard intracellular solution. A I_slow started to develop several seconds after the photocurrent (which was truncated, as its amplitude of several nA would fall off-scale at this gain). Holding potential of −60 mV. (D) Slow after-current in three different cells to illustrate the variability in amplitude and time course. (E) Repetitive activation of I_slow in the same cell, exposed to a flash attenuated by 0.6 log compared with the trace in C and D. (F) I_slow obtains in photoreceptors voltage clamped by the perforated patch technique. The two examples show the current evoked by a 100-ms flash (1.4 × 10¹⁵ photons × cm⁻² × s⁻¹) in photoreceptor cells in which access to the cytoplasmic compartment was attained by adding the pore-forming agent nystatin to the pipette filling solution, or β-escin. In all these examples, the extracellular solution was ASW.