APStracts 3:0135H, 1996.

Reflex vascular responses to abdominal venous distension in the anesthetised dog. Doe, Cpa, Mj Drinkhill, Ds Myers, Da Self, and R Hainsworth. Institute for Cardiovascular Research, University of Leeds, Leeds LS2 9JT, UK and Crew Technology Division, Armstrong Laboratory, Brooks AFB, Texas, USA, Tel No: + 1132334820, Fax No: + 113 2334803

APStracts 3:0135H, 1996.

This study was undertaken to determine whether distension of the subdiaphragmatic veins results in reflex vasoconstriction and interacts with the carotid baroreflex. In chloralose anesthetized, open-chest dogs, a perfusion circuit contolled carotid sinus and thoracic aortic pressures, splanchnic and limb blood flows and cardiopulmonary blood flows. At carotid sinus pressures below about 90 mmHg increases in splanchnic venous pressure of 7 mmHg or more resulted in increases in vascular resistance in both the splanchnic and limb circulations; there was no response at higher carotid pressures. At high venous pressures the average maximum gains of the carotid baroreflex for splanchnic and limb resistance responses were increased by 106 and 67% respectively. The responses were not abolished by cutting the vagal or phrenic nerves but were prevented by cutting the splanchnic nerves and for the limb the sciatic and femoral nerves. These results suggest that splanchnic congestion, by causing vasoconstriction and augmentation of the carotid baroreflex, may be important in the maintenance of blood pressure during gravitational stress.

Received 23 October 1995; accepted in final form 22 March 1996.
APS Manuscript Number H989-5.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 1 April 96