Fig. 2.
Effects of calmodulin (CaM) on wild-type and RyR2-L3591D single-channel activities. Membranes isolated from the hearts of wild-type and Ryr2D/D mice were fused with a lipid bilayer. Top: single-channel currents were recorded at −35 mV in the presence of 0.2 μM (A) and 2 μM (B) cis cytosolic Ca2+ as described in materials and methods in the absence of CaM (top) and on the subsequent addition of 50 nM (middle) and 1 μM (bottom) cis CaM. Po, open channel probability. Bottom: mean ± SE Po of number of recordings indicated in parentheses, normalized to control. *P < 0.05, **P < 0.001 compared with control (no CaM added). Mean Po in absence of CaM were 0.08 ± 0.02 (n = 10) and 0.10 ± 0.07 (n = 8) at 0.2 μM Ca2+ and 0.55 ± 0.05 (n = 15) and 0.47 ± 0.12 (n = 8) at 2 μM Ca2+ for wild-type and RyR2-L3591D channels, respectively.