Angiotensin II is concentrated or locally produced in rat adrenal gland

1. Angiotensin II (AII) has been traditionally regarded as a circulating hormone with major actions on vascular tone and aldosterone secretion. However, renin occurs in many extrarenal tissues and some evidence for local formation of AII has been presented for organs such as brain, kidney and blood vessels. 2. A peptide closely resembling AII has been detected in rapidly frozen rat adrenal. The levels found greatly exceed that which can be accounted for by blood contamination. 3. Twenty-four hours after bilateral nephrectomy, rats had undetectable plasma renin activity and plasma angiotensin II levels. At this time, adrenal AII was lower than in sham-operated animals but was still present at significant concentrations. 4. These results suggest that AII may be either concentrated or locally produced in the adrenal. The activity of the renin-angiotensin system in plasma cannot be used to make inferences regarding AII concentration at the adrenal.