Evidence for local angiotensin formation in brain of nephrectomized rats

Twenty-four nephrectomized rats were infused intracranially with angiotensin II (AII), synthetic tetradecapeptide substrate and purified rat and dog plasma substrates. Significant drinking responses were observed with all four substances. Drinking to the renin substrate infusions was inhibited by intracranial infusions of either angiotensin I-converting enzyme inhibitor (SQ 20881) or a specific AII antagonist, saralasin, indicating that conversion of the substrates to AII was a necessary step in order to produce the drinking responses. These results indicate that brain iso-renin can operate under physiological conditions to produce angiotensin from both synthetic and naturally occurring substrates.