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.

Dopamine topically applied to the cerebral cortex (1--20 micrograms/ml) or administered i.v. (0.5--64 micrograms/kg/min) has no effects on cerebral cortical blood flow in the rat.