Studies in rats were designed to separate and define the roles of the intrinsic and extrinsic adrenergic neurons in the control of cerebral blood flow (CBF) and cerebral energy metabolism. The data suggest several conclusions:
1. Arterial sympathetic innervation plays a role in the autoregulation of cerebral circulation.
2. The central adrenergic neurons have several functions: a) they enhance cerebral vascular tone by action on alpha receptor sites, b) They play an important role in the metabolic control of CBF. The proton-sensitive receptor sites on blood vessel walls require beta-adrenergic input in order to function, c) They influence metabolic rate of brain tissue by acting on beta-receptor sites on the cell membrane.