Fig. 4. Time course of the effect of intravenous (i.v., open circles) and intracranial (i.c., filled circles) administration of eel angiotensin II (eANG II). The dose of eANG II, 10^-7 mol i.v. and 5x10^-11 mol i.c., was chosen to obtain similar enhancement of water intake. For comparison, the time course of the effect of intracranial eel atrial natriuretic peptide (eANP, filled squares) is also shown. Water intake was measured every 5 min, and expressed as mean ± S.E.M. ^*P<0.05, ^**P<0.01, compared with the value before administration at time zero (paired t-test).