Fig. 3. Water samples taken every 5 min from a separate group of -methyl-5-HT-injected fish, demonstrating that the agonist injection results in a significant and pulsatile increase in the excretion of urea within 5 min. Inset shows coarser time scale for comparison with Fig. 2. All values are means ± 1 S.E.M. (N=6); *P<0.05, significantly different from value at t=0.