Fig. 2. Dose—response curves of the effect of eel angiotensin II (eANG II; filled circles), isoproterenol (filled triangles) and acetyl choline (Ach; open circles) on water intake by seawater eels. Water intake was measured during a 20 min period after administration of the ligand, and is expressed as % of the control rate measured during a 20 min period before administration (100%). The injection rate was 1.25 µl min^-1 for 4 min. Values are means ± S.E.M. Number of experiments is indicated in parentheses. ^*P<0.05, ^**P<0.001, compared with the control value (paired t-test).