AJP - Heart and Circulatory Physiology, Vol 233, Issue 5 587-H591, Copyright © 1977 by American Physiological Society
Effect of a left atrium-pulmonary vein baroreflex on peripheral vascular beds
T. C. Lloyd Jr and J. J. Fried
A step increase of left atrial and pulmonary venous pressure from 0 to 25
mmHg was used in anesthetized dogs with controlled arterial blood pressure
to generate reflex systemic vasodilation. The resultant response of total
peripheral resistance was an initial transient fall of about 40% which
spontaneously regressed while the stimulus was maintained. Injections of
differently tagged radioactive microspheres were used to measure selected
organ blood flows prior to raising atrial pressure, at the response peak,
during the steady state, and after recovery. Resistances of skin, skeletal
muscle, kidney, and large intestine significantly fell upon atriovenous
distention. The response in muscle, which greatly exceeded that of the
other organs, was not sustained, whereas resistances of other responding
beds remained depressed until the stimulus was removed. No significant
responses occurred in small intestine, liver (hepatic artery), or adrenal
gland.
