Fig. 6. Percentage change (mean ± 1 S.D.) in responses of EOD waveform parameters to injection of serotonin at doses 2.5 nmol g^-1, or to saline controls. EOD parameters were measured as in Fig. 2. Means were compared with two-sample t-tests; the P values shown are one-tailed. Compared to the controls, serotonin caused significant increases in amplitude, second phase duration (dur-P2), and second phase repolarization time (-P2), but not of first phase duration (dur-P1).