Cholinergic Control of Blood Flow in the Cerebral Cortex of the Rat• Local blood flow was measured in the somatosensory cortex of urethanized rats by means of the hydrogen clearance method. The variations of cortical blood flow in the course of the anesthesia and the effects of the topical application of atropine, eserine and cholinomimetic drugs were studied. During urethan anesthesia, the electrical activity of the cerebral cortex fluctuated between a synchronized and a desynchronized state. During desynchronization, local cortical blood flow increased significantly. This increase in blood flow could be prevented by topical application of atropine and exaggerated by topical eserine. Topical application of arecoline, carbaminoylcholine, pilocarpine or acetylcholine with eserine significantly increased cortical blood flow. It is concluded that the increase in cortical blood flow that accompanies cortical desynchronization in the urethanized rat is mediated, at least in part, by a neurogenic mechanism that involves a cholinergic step at the cortical level.

Abstract:Cholinergic Mechanism in the Cerebrovascular Action of Carbon Dioxide• The effect of an increase in Pa^., on cortical blood flow was tested in control animals and after atropine or eserine administration. Blood flow was measured at the tip of implanted platinum electrodes by means of the hydrogen clearance method. The results showed that, although atropine did not impede the appearance of autoregulation, it completely blocked the increase in cortical blood flow associated to a step increase in Pa,. o .,. The effect of CO 2 on cortical blood flow was significantly greater under eserine than in untreated controls.Additional Key Words atropine cortical blood flow eserine CO, cholinergic

Cerebral cortical blood flow was measured with the hydrogen clearance technique. It was found that the increase in CoBF induced by amphetamine is blocked by atropine or chlorpromazine.

No abstract