Fig. 6.

Ro 90–7501 effect on Ca²⁺ spark rate in permeabilized rat myocytes. (A) Representative paired line-scan recordings (6 s) of Ca²⁺ sparks response to acute exposure (5 min) to 10 μM Ro 90–7501 or 500 μM tetracaine treatment, as indicated, under either control (Ctrl) conditions or following 50 μM H₂O₂ pretreatment (1 h). Colour display scales span the fluorescence range of Ca²⁺ sparks. (B) Time course of average (±SEM, n/N (# of cells/# of animals) = 7/4 Ctrl, 9/4 Ro 90–7501) Ca²⁺ spark frequencies (CaSpF) with and without 10 μM Ro 90–7501 treatment over 5 min (repeated measures two-way ANOVA with Geisser-Greenhouse correction; Dunnett multiple comparison post-hoc test). (C) Explicit paired comparisons of CaSpF before or after 5 min exposures to either Ro 90 or tetracaine, with or without H₂O₂ pretreatment (Wilcoxon matched-pairs rank tests, n/N = 13/7, 8/3 and 7/3, respectively). (D) CaSpF for individual groups, including unpaired measures, analyzed via one-way ANOVA vs. Ctrl and Dunnett’s multiple comparison post-hoc test (n/N = 28/11, 15/7, 8/3, 9/3, 7/3, respectively). (E) Percent change in average Ca²⁺ spark frequency and amplitude relative to respective control averages, and in average SR Ca²⁺ load relative to control average. Statistical analyses were performed using GraphPad Prism 9 software.