[Double cholinergic and adrenergic regulation of cerebral blood flow]

Cerebral vascular tonus was measurably influenced by both alpha or beta adrenergic blockade and by inhibition of cerebrovascular acetylcholine or acetylcholinesterase. Cerebral autoregulatory response was significantly affected by intravenous injection of PBZ, intravertabral and intravenous injection of PPL and intravertebral and intracarotid injection of neostigmine. Cerebral vasomotor reactivity to changes in aPCO2 was altered significantly by intravertebral injection of PPL, atropine, and neostigmine. The doses of intravenous PBZ injections were large (1.5 mg/kg) so that PBZ not only blocked peripheral alpha adrenergic receptor sites in the cerebrovascular system but probably also those possibly located in the brain stem (vertebrobasilar territory). The functional significance of a double cholinergic and adrenergic neuronal system located in the brain stem influencing CBF appears to have been established.