Localization of central sites of action of angiotensin II on ADH release in vitro

Abstract

Angiotensin II apparently can stimulate antidiuretic hormone (ADH) release in vivo by a direct action in the CNS, but it is not known whether the locus of stimulation is the hypothalamus or the neurohypophysis or both. Isolated rat neural lobes incubated for 10 min in buffer containing angiotensin II (200 ng/ml or 2 .mu.g/ml) did not increase ADH release compared to control values, but addition of KCl (60 mM) to the bath markedly stimulated ADH release. Intact hypothalamoneurohypophysial systems (containing the supraoptic nuclei) incubated with angiotensin II (200 ng/ml or 2 .mu.g/ml) did show a pronounced stimulation of ADH release. Angiotensin II, at least in vitro, apparently has a central effect on ADH release which is at the level of the hypothalamus.