A. Representative traces of 1 Hz stimulus evoked end plate currents (EPC) of control (a and c), + CAP (b), + CPZ (d), and + CPZ + CAP (e) treated nerve muscle preparations (n = 4–6, 16–22) at the end of 120 min. after the application of either vehicle alone or the drug. CPZ was pretreated and was present throughout the experiments (d and e). B. EPC amplitudes ± S.E.M of control (a and c), + CAP (b), + CPZ (d), and + CPZ + CAP (e) treated nerve muscle preparations (n = 4–6, 16–22). C, D and E. Represent the spontaneous miniature end plate current (mEPC) amplitude, frequency and quantal content of control, + CAP, + CPZ + CAP, and + CPZ treated preparations. Numbers in parentheses represent the numbers of nerve muscle preparations and fibers respectively obtained from six mice for each condition. (Quantal content = ratio of EPC amplitude to mEPC amplitude). ** represents statistical significance for P<0.001.