Figure 3.

Effect of 4-CEP on [Ca²⁺]_i and contraction in skeletal muscle cells. [Ca²⁺]_i was measured as described in Materials and Methods. (A) 4-CEP induced an increase in [Ca²⁺]_i that reversed on washout. (B) Tetanic contraction was produced by giving a train (300 ms) of supramaximal current pulses (0.5 ms) at 100 Hz. The forces of contractions before addition of 4-CEP and after 8 min of exposure to the substance and washout were equal in magnitude. (C) β-Alanyl ryanodine (10 μM) did not increase [Ca²⁺]_i. The traces are representative of three to four experiments.