CENTRAL ANGIOTENSIN-CONVERTING ENZYME-BLOCKADE AND THIRST

1. The effect of lisinopril, a potent inhibitor of angiotensin convert ing enzyme (ACE), injected into the medial preoptic area (MPOA) on wat er intake was investigated in male Holtzman rats (200-250 g). 2. Injec tion of lisinopril (2 mug/mul) into the MPOA abolished the water intak e induced by subcutaneous (sc) injection of isoprenaline (100%) and wa ter deprivation (90%) and drastically reduced the water intake induced by sc injection of polyethyleneglycol (60%). A small reduction of wat er intake induced by lisinopril was also observed 90 and 120 min after sc hypertonic saline (N = 10 for each group). 3. These results sugges t that central ACE activation, particularly in the MPOA, plays an impo rtant role in the dipsogenic responses induced by the agents studied.