Neurogenic control of cerebral blood flow in the baboon.

Cerebral chemical vasomotor reactivity and autoregulation were tested in normal baboons before and after the intravenous or intravertebral infusion of atropine sulfate (0.02 mg/kg). Atropine did not appreciably effect autoregulatory response, but intravertebral injection suppressed the increase of cerebral blood flow (CBF) by inhalation of 5% CO2 and enhanced the decrease of CEF induced by hyperventilation. These changes produced by intravertebral injection of atropine were not observed after intravenous injection. Since the vertebrobasilar arterial system supplies the brain stem and diencephalon, this suggests that a central vasodilator tonus of the cerebral vessels is maintained by the innervation of the cerebral vessels by cholinegic neurons which have their central origin in the brain sterm and diencephalic area.