Relative change in the amplitude of peak SR Ca ²⁺ release flux following probenecid (or control solution) application and wash-out. Data are from the same experiments as in Fig. 6. Individual values from each fiber, and corresponding mean (±SD) values, for the relative change in peak SR Ca²⁺ release flux following application of the control solution (control-test, left) or of the probenecid-containing solution (probenecid-test, right) and after wash-out. Values in each fiber were normalized to the corresponding peak SR Ca²⁺ release flux in the initial control condition. Graphs from top to bottom report the changes at the three tested voltages.