Affiliation:
1. Department of Pharmacology, University of Vermont, Burlington, Vermont, U.S.A.
Abstract
Using standard in vitro techniques, we found that the canine retroglenoid vein, a vessel that drains a significant fraction of canine cerebral venous effluent, demonstrated the following: an average wall thickness of ∼240 μm; a norepinephrine (NE) content of ∼3 μg/g tissue; a NE uptake capacity (uptake 1) of ∼8 nmol/g tissue; an ED50 for NE of 1.9 × 10−8 M; and a phentolamine-sensitive constriction during electric transmural stimulation that had a median effective frequency of ∼3 Hz and a maximum response that was ∼84% of the maximum response to exogenous NE. In a separate series of in vivo experiments conducted in six α-chloralose-anesthetized dogs, we found that electrical stimulation of the left superior cervical ganglion produced a phentolamine-sensitive, frequency-dependent increase in cerebral venous pressure (CVP) of up to 19 mm Hg when all cerebral venous effluent was diverted through the left retroglenoid vein. Taken together, our findings suggest that the canine retroglenoid vein undergoes a marked vasoconstriction during physiological frequencies of electric sympathetic nerve stimulation in vivo. Although our data further suggest that the retroglenoid is not a dominant influence on CVP in the intact dog, they do encourage a cautious interpretation of cerebral venous outflow data obtained with techniques in which cerebral effluent is drained primarily by extracranial veins.
Subject
Cardiology and Cardiovascular Medicine,Neurology (clinical),Neurology
Cited by
7 articles.
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