Sodium appetite elicited by intracerebroventricular infusion of angiotensin II in the rat: I. Relation to urinary sodium excretion.

Intracerebroventricular infusion of angiotensin II (Ang II) elicits a substantial sodium appetite in the rat. The present results demonstrate that this phenomenon consists of a small, early phase of sodium ingestion that is not the result of prior sodium loss but that thereafter urinary excretion of sodium exceeds intake and consequently the animals become hyponatremic and hypovolemic. The larger and more sustained bouts of sodium ingestion occurring 8-12 hr after the start of the Ang II infusion appear to represent a behavioral compensation for this incurred sodium deficit. These results confirm the arousal of a sodium appetite by action of Ang II on the brain but indicate the need for caution in assigning to it a direct and exclusive role in the neuroendocrine control of sodium intake.