Figure 6.

Effects of caffeine and ATP on RyR1-WT and RyR1-E3893Q/E3967Q, E3893V/E3967V, and T5001A variant channel open probabilities in presence of cytosolic Ca²⁺. A, representative single-channel currents are shown at −20 mV as downward deflections from the closed state (c−) in symmetrical 0.25 m KCl. Luminal Ca²⁺ was 2 μm. Free cytosolic Ca²⁺ was 30 μm (top traces) and 5 μm (as described under “Experimental procedures”) after the addition of 5 mm caffeine and 2 mm ATP (+A/C) (bottom traces). B, -fold increase of P_o after the addition of 5 mm caffeine plus 2 mm ATP. Data are the mean ± S.E. (error bars) of six recordings. *, p < 0.05 compared with respective controls by two-way ANOVA followed by the Holm–Sidak method.