Figure 8.

Effects of Ca²⁺-free perfusion in itpr-null photoreceptors are similar to those of controls. A, Responses to brief flashes containing ∼25 effective photons recorded with EGTA-buffered electrode solutions before (dotted traces), 10 s after (larger slow responses), and 200 s after perfusing with Ca²⁺-free solution (1 mm EGTA). B, C, The reduction in peak amplitude (log₁₀ scale) after 10- and 200-s perfusion and slowing of the response (measured by time to peak after 10- to 60-s perfusion) were similarly affected in itpr-null mosaic and itpr/+ sibling controls (p = 0.2–0.7, two-tailed t tests). D, Time course of suppression of the light response in Ca²⁺-free solution was similar in itpr-null mosaics and controls (mean ± SEM, n = 9–12 cells). E, Same data plotted on log₁₀ scale.