Angiotensin II immunoreactivity in push-pull perfusates from the paraventricular nucleus

Push-pull perfusion of the hypothalamic paraventricular nucleus in sodium pentobarbital anesthetized Sprague-Dawley rats indicates the release of angiotensin II-immunoreactive material in this area. Attempts to demonstrate a neuronal origin of this material by chemical depolarization with perfusate containing either 40 or 120 mM K+ were unsuccessful. However, this material does appear to be of central origin since intravenous infusion of arginine-vasopressin, a similar sized peptide, did not result in the appearance of increased levels of this substrate in the perfusate, indicating that the integrity of the blood-brain barrier was not compromised by the perfusion.