Role of adrenergic structures in functional control over the cerebral circulation.

An investigation of the cerebral circulation by the thermoelectric method showed that stimulation of the cervical sympathetic nerve leads to considerable changes in the blood supply to the brain. The changes in blood flow are biphasic in character: An initial small increase is followed by a decrease below the original level. Pharmacological analysis with alpha and beta adreno-blockers showed that the constrictor response of the cerebral vessels is due to excitation of alpha-adrenergic structures and the dilator response to excitation of beta-adrenergic structures. A possible mechanism of these changes is postulated.