Cephalic angiotensin receptors mediating drinking to systemic angiotensin II.

In rats implanted with cannulae to allow delivery of solutions to the cerebral ventricular system, pretreatment with 5 mug or 0.5 mug of saralasin acetate (Sar1 Ala8 Angiotensin II), an angiotensin II competitive analog, significantly attenuated drinking to subcutaneous (SC) injections of 500 mug of angiotensin II. However, pretreatment with either SC (5 mug or 20 mug) or with intravenous (5 mug) saralasin had no effect on drinking to SC angiotensin II (500 mug). Intracranial (IC) injections of 5 mug of saralasin had no effect on drinking in response to SC injections of 0.8 cc of a 10 percent NaCl solution and did not attenuate ingestion of a milk solution in a dessert test. On the basis of the specificity and the greater efficacy shown by IC saralasin in attenuating drinking to systemically applied angiotensin II, it was concluded that circulating angiotensin II reaches brain periventricular receptors which mediate drinking.