Effect of angiotensin and atropine on the spontaneous release of acetylcholine from cat cerebral cortex

Abstract

The effect of angiotensin and atropine was studied on cortical acetylcholine output in the cat ‘encéphale isolé’ preparation. Acetylcholine was estimated by bioassay. Local administration of either of these 2 drugs at a concentration of 10 −9 M caused an increase of acetylcholine output from the parietal cortex, an effect that persisted after washing. At 10 −8 M, angiotensin caused a 240% increase of acetylcholine output, while atropine, at the same molar concentration, did not change the initial output of acetylcholine. Intracortical administration of 1 ng og angiotensin also increased the acetylcholine output (85%), while a same volume of isotonic NaCl solution did not change the initial output. Brain cholinesterase activity, as measured by the gazometric method, was not depressed by angiotensin. It is postulated that the effect of angiotensin on acetylcholine output is due to changes in the release mechanism.