Evidence for a dopaminergic mechanism for the diuretic and natriuretic action of centrally administered atrial natriuretic factor.

1. Intracerebroventricular (IVT) administration of rat atrial natriuretic factor (ANF) (99-126) to conscious male hydrated rats induces a dose-dependent increase in urine and sodium excretion. The possible involvement of brain dopaminergic system in the IVT-ANF-induced diuresis and natriuresis was evaluated. 2. Central sympathectomy (6-OHDA, 250 micrograms/5 microliters, IVT; 72 and 48 hr before IVT-ANF) inhibited both the diuretic and the natriuretic action of centrally administered ANF, suggesting that in the brain ANF requires the integrity of central noradrenergic and/or dopaminergic systems function for its actions. 3. Intracerebroventricular injection of haloperidol and intragastric administration of domperidone prevent the diuretic and natriuretic response to centrally administered ANF. 4. Our data suggest a neuromodulatory action of ANF within the brain and demonstrate an interaction of the peptide with brain dopaminergic systems.