Influence of endogenous norepinephrine on cerebral blood flow and metabolism.
The influence of brain norepinephrine on cerebral metabolism and blood flow was examined because exogenous norepinephrine, administered in a way that the blood-brain barrier is bypassed, has been shown to effect pronounced changes in the cerebral circulation. Reserpine (40 mug/kg, by intracarotid infusion) was administered in order to release brain norepinephrine in five anesthetized baboons. Reserpine significantly increased cerebral oxygen consumption (23%) and cerebral blood flow (50%). This response lasted for approximately 60 min. In a further  five animals, effects of central beta-adrenoreceptor blockade were studied. Pro pranolol (12 mug/kg-min) produced an immediate, significant reduction in both cerebral oxygen consumption (40%) and cerebral glucose uptake (39%). Cerebral blood flow was reduced minimally. However, the responsiveness of the cerebral circulation to induced hypercapnia was severely attenuated from a gradient of 3.22 before, to 1,11 after, administration. These experiments suggest that central norepinephrine can influence the cerebral circulation primarily through noradrenergic effects on brain metabolism.
D000818:Animals; D001921:Brain / Q000378:metabolism*; D002245:Carbon Dioxide / Q000097:blood; D002560:Cerebrovascular Circulation / Q000187:drug effects; D005947:Glucose / Q000378:metabolism*; D009638:Norepinephrine / Q000502:physiology*; D010101:Oxygen Consumption / Q000187:drug effects; D010215:Papio / Q000378:metabolism*; D011433:Propranolol / Q000494:pharmacology; D012110:Reserpine / Q000494:pharmacology
D002245:Carbon Dioxide; D012110:Reserpine; D011433:Propranolol; D005947:Glucose; D009638:Norepinephrine