Figure 4.

Sparks and long openings induced by Ry. (A) Normalized line-scan image in a permeabilized fiber immersed 15 min in internal solution with 50 nM Ry. Traces plot F/F₀ averaged over a 0.7 μm-wide region. Note the long openings, beginning with a starter or, occasionally, without one (black). (B) After ≈50-min exposure frequency of sparks and amplitude of starters decreases. Very long-lasting events are present. (C) Example event that decays in two steps. Identifiers were 1012a66, 1015a60, and 1025a112.