Fig. 3.

Absence of DHPR-mediated Ca²⁺ influx has no impact on SR Ca²⁺ store content. a Representative trace of SR Ca²⁺ release in intact interosseous muscle fibres triggered by application (green arrow) of 500 µM of RyR agonist 4-CmC in the presence of 30 µM of SERCA blocker CPA. The resulting Ca²⁺ signals were measured with the low affinity indicator Fura-FF-AM to avoid dye saturation during Ca²⁺ release stimulation. b Comparison of 4-CmC-induced Ca²⁺ signals, measured as peak fluorescence ratio of Fura-FF (340/380) showed no significant difference (P > 0.05) between ncDHPR (1.0 ± 0.02; n = 53) and wt muscle fibres (1.04 ± 0.02; n = 48), indicating identical SR Ca²⁺ store filling. Bars represent mean ± s.e.m.; P determined by unpaired Student’s t-test