Figure 3.

[³H]Ryanodine binding of RyR1 in choline chloride (choline Cl) and NaCl media.A, specific [³H]ryanodine binding to RyR1 was determined in 0.5 M choline Cl or 0.5 M NaCl, 20 mM imidazole, pH 7 with 2 nM [³H]ryanodine and the indicated Ca²⁺ in the absence and presence of 2 mM AMPPCP and/or 5 mM caffeine (Caf). B and C, specific [³H]ryanodine binding to RyR1 was determined in 0.5 M choline Cl or 0.5 M NaCl, 20 mM imidazole, pH 7 with 5 nM [³H]ryanodine and nominally 0.01 μM Ca²⁺ (B) and 25 μM Ca²⁺ (C) before and after the addition of 2 mM AMPPCP and/or 5 mM Caf. Data are the mean ± SE of four to five experiments (B) and mean ± SD of three experiments (C). #p < 0.05 compared with Ca²⁺ only by two-way ANOVA followed by Holm–Sidak method. Labels used in the figure: A refers to ATP, C refers to Caf, and AC refers to ATP + Caf. RyR1, ryanodine receptor type 1.