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Sites at which vasopressin facilitates baroreflex inhibition of lumbar sympathetic nerve activity
Journal article   Peer reviewed

Sites at which vasopressin facilitates baroreflex inhibition of lumbar sympathetic nerve activity

Gary B Guo, Phillip G Schmid and Francois M Abboud
The American journal of physiology, Vol.251(3 Pt 2), pp.H644-H655
09/1986
DOI: 10.1152/ajpheart.1986.251.3.H644
PMID: 3752274

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Abstract

We recently reported that intravenous vasopressin in anesthetized rabbits facilitates baroreflex inhibition of lumbar sympathetic nerve activity. The purpose of this study was to determine the possible sites of this facilitation. We found that intravenous infusion of vasopressin (16-32 mU X kg-1 X min-1) caused greater inhibition of lumbar sympathetic nerve activity than did phenylephrine for a given increase in aortic baroreceptor activity, suggesting a "central" action of vasopressin. A central action was supported also by the observation that the carotid baroreflex inhibition of lumbar sympathetic nerve activity was augmented by intravenous infusion of vasopressin when the carotid sinuses were isolated, filled with saline, and distended (aortic depressor and vagal nerves were cut). On the other hand, vasopressin also facilitated baroreflex inhibition of lumbar sympathetic nerve activity through an influence on arterial baroreceptors, because intravenous vasopressin caused greater afferent activity of the aortic depressor nerve per unit rise in arterial pressure than did phenylephrine. In a separate group of rabbits, intravenous infusion of vasopressin also elevated the level of afferent aortic depressor activity during increases in arterial pressure induced by intra-aortic balloon inflation. Furthermore, when vasopressin was confined to the isolated carotid sinuses, the reflex inhibition of lumbar sympathetic nerve activity during distension of carotid sinuses was augmented. We conclude that circulating vasopressin facilitates baroreflex inhibition of sympathetic nerve activity through a central nervous system action as well as through an effect on arterial baroreceptors.
 Rabbits Sympathetic Nervous System - drug effects Infusions, Parenteral Reflex - drug effects Vasopressins - pharmacology Male Brain - physiology Neurons, Afferent - physiology Animals Lumbosacral Region Aorta - innervation In Vitro Techniques Administration, Topical Neural Inhibition - drug effects Carotid Sinus - drug effects Pressoreceptors - drug effects

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