The Role of the Peripheral Sympathetic Nervous System in Cerebral Blood Flow Autoregulation

Abstract

Abstract:The Role of the Peripheral Sympathetic Nervous System in Cerebral Blood Flow A utoregulation• The effect of chronic, unilateral superior cervical ganglionectomy on cerebral blood flow and blood flow autoregulation to changes in perfusion pressure was examined in seven phencyclidine anesthetized monkeys. Ten to 14 days prior to the experiments Doppler ultrasonic flow transducers were placed on both carotid, arteries after ligation of the external carotid branches and removal of one superior cervical ganglion. Autoregulation was tested by exsanguination and metaraminol infusion with the monkeys inspiring room air, 9% and 12% carbon dioxide in air. Immediately following experimentation the cerebral vessels were examined for the presence of noradrenergic fibers. The results of the study demonstrate that: (1) superior cervical ganglionectomy produces a significant reduction in the noradrenergic innervation of ipsilateral extraparenchymal arteries; (2) the peripheral sympathetic nervous system contributes to overall cerebral vascular resistance primarily by affecting resistance in extraparenchymal arteries; and (3) as a result, it determines the contribution of the extraparenchymal arteries to overall cerebral blood flow autoregulation.

Cerebral blood flow autoregulation in the rat.

“…18 3 have also recently reported that X for this indicator in rat cerebral cortex is comparable to that in humans. The present CBF values in Sprague-Dawley rats, under normocarbic, normoxic, and normotensive conditions, are similar to those reported in rats of the Wistar strain.…”

“…Although Kahn followed the natural course of stroke in gerbils for more than 24 hours, 3 he did not describe variability of the clinical manifestations and little attention has been drawn in the literature to this important phenomenon. The clinical manifestations of stroke and the variability of protein synthesis were studied together to emphasize the importance of clinical observation in addition to biochemical study.…”

Effect of acute exposure to hypergravity (GX vs. GZ) on dynamic cerebral autoregulation

“…For example, in primates, both unilateral superior cervical ganglionectomy and alpha adrenergic blockade with intravenous r------l 12 phenoxybenzamine enhance the maintenance of CBF in the face of hypotension, shifting the autoregulation curve acutely to the left (7,14) and impairing the autoregulatory response to acute increases in BP (14,44). However, these effects are mainly reversed after chronic sympathectomy (7,11). Moreover, stimulation of the cervical sympathetic nerve in primates acutely decreases CBF (13,20) while shifting the autoregulation curve to the right (13 , 17).…”

Effect of cerebrospinal fluid removal on cerebral blood flow and metabolism in patients with Alzheimer's disease versus recent stroke.

“…It should be recognized, however, that other studies have shown that while the autonomic nervous system may modify CBF autoregulation, it is not responsible for the existence of the basic phenomenon. 22 There have been few studies made concerning autoregulatory mechanisms when ICP is reduced by removal of CSF. Under normal circumstances CBF remains constant when CSF is removed even in patients with benign intracranial hypertension.…”