Figure 5.

Effect of HdCa (hadrucalcin) on the Ca²⁺ dependence of [³H]ryanodine binding to skeletal and cardiac ryanodine receptors. The Ca²⁺ dependence of [³H]ryanodine binding to sarcoplasmic reticulum vesicles of rabbit skeletal muscle (A) or dog cardiac sarcoplasmic reticulum (B) in the absence (open circles) and the presence (filled circles) of 100 nmol·L⁻¹ HdCa. Binding conditions were as described in Methods. Smooth lines are Bezzier fittings to the data points. Data in both panels represents the mean ± SE for n= 4 (A) and 3 (B) determinations.