Walsh & Hoyt: Autoregulation of Cerebral Blood Flow

The cerebrovascular bed is at all times subject to the combined influence of a number of physical and chemical stimuli that adjust vascular caliber so as to alter the blood supply to different parts of the brain and may be of local or systemic origin. There are three mechanisms that assist in the autoregulation of CBF (196198). First, arterial smooth muscle responds directly to variations of blood pressure by constricting or dilating, thus changing the diameter of the vessel lumen. Second, local concentrations of metabolites directly affect vascular tone. Because any change in blood flow causes cellular metabolites to be carried away at a different rate, vascular tone changes, and the size of the vascular lumen is altered accordingly. Lastly, autonomic neural influences of local or remote origin may control vascular tone, changing the size of the arterial lumen.