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Effects of decreasing arterial blood pressure on cerebral blood flow in the baboon. Influence of the sympathetic nervous system.
Metadata
Journalcirculation research14.467Date
1975-Nov
Publication Type
Journal Article
Volume
1975-Nov / 37 : 550-7
Author
Fitch W , MacKenzie ET , Harper AM
DoiPMIDMESH
Adrenergic alpha-Antagonists
Animals
Blood
Blood Pressure
Blood Transfusion
Carbon Dioxide
Cerebrovascular Circulation
Haplorhini
Hemorrhage
Homeostasis
Hydrogen-Ion Concentration
Hypotension
Papio
Phenoxybenzamine
Sympathectomy
Sympathetic Nervous System
Abstract
The influence of the sympathetic nervous system on the cerebral circulatory response to graded reductions in mean arterial blood pressure was studied in anesthetized baboons. Cerebral blood flow was measured by the 133Xe clearance method, and arterial blood pressure was decreased by controlled hemorrhage. In normal baboons, the constancy of cerebral blood flow was maintained until mean arterial blood pressure was approximately 65% of the base-line value; thereafter, cerebral blood flow decreased when arterial blood pressure was reduced. Superior cervical sympathectomy of 2-3 weeks duration did not affect the normal response. In contrast, both acute surgical sympathectomy (cervical trunk division) and alpha-receptor blockade (1.5 mg/kg of phenoxybenzamine) enhanced the maintenance of cerebral blood flow in the face of hemorrhagic hypotension in that cerebral blood flow did not decrease until mean arterial blood pressure was approximately 35% of the base-line value. The results indicate that the sympathetic nervous system is not involved in the maintenance of cerebral blood flow in the face of a fall in arterial blood pressure. Indeed, the implication is that the sympathicoadrenal discharge accompanying hemorrhagic hypotension is detrimental to, rather than responsible for, cerebral autoregulation.
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14.5
Circ Rescirculation research
Metadata
LocationUnited States
FromLIPPINCOTT WILLIAMS & WILKINS

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