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Role of venoconstriction in the cardiovascular responses of ducks to head immersion

Role of venoconstriction in the cardiovascular responses of ducks to head immersion METHODS PROLONGED SUBMERSION vertebrates results in major cardiovascular adjustments that include a pronounced bradycardia and a fall in cardiac output to below one-fourth of normal resting levels (24). A massive peripheral vasoconstriction maintains at nearly normal levels, but this constriction occurs preferentially, so that blood flow reductions occur in beds that can utilize anaerobic pathways (skin, muscles, gut, etc.). On the other hand, tissues dependent on aerobic metabolism, notably brain, are not constricted. The heart is on aerobic metabolism, although the also dependent decline in cardi .ac output results in reduced energy requirements that give rise to coronary vasoconstriction in some species (32). In addition to the above changes, submersion of aquatic birds results in large increases in central (21, 22), however the causes and the consequences of this increase are not well established. Central could conceivably be elevated by shifts by a possible of fluid volu .me from other compartments elevation of intrathoracic during apnea or by a redistribution of vascular s secondary to ternatively, elevated olar vasoconstriction. res during divin .g may reflect a venomotor Experiments were performed on 2.8 (Anas species) of either sex, weighing from 0.8 to 2.2 kg. during head immersion; effect of http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png AJP - Regulatory, Integrative and Comparative Physiology The American Physiological Society

Role of venoconstriction in the cardiovascular responses of ducks to head immersion

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Publisher
The American Physiological Society
Copyright
Copyright © 1983 the American Physiological Society
ISSN
0363-6119
eISSN
1522-1490
Publisher site
See Article on Publisher Site

Abstract

METHODS PROLONGED SUBMERSION vertebrates results in major cardiovascular adjustments that include a pronounced bradycardia and a fall in cardiac output to below one-fourth of normal resting levels (24). A massive peripheral vasoconstriction maintains at nearly normal levels, but this constriction occurs preferentially, so that blood flow reductions occur in beds that can utilize anaerobic pathways (skin, muscles, gut, etc.). On the other hand, tissues dependent on aerobic metabolism, notably brain, are not constricted. The heart is on aerobic metabolism, although the also dependent decline in cardi .ac output results in reduced energy requirements that give rise to coronary vasoconstriction in some species (32). In addition to the above changes, submersion of aquatic birds results in large increases in central (21, 22), however the causes and the consequences of this increase are not well established. Central could conceivably be elevated by shifts by a possible of fluid volu .me from other compartments elevation of intrathoracic during apnea or by a redistribution of vascular s secondary to ternatively, elevated olar vasoconstriction. res during divin .g may reflect a venomotor Experiments were performed on 2.8 (Anas species) of either sex, weighing from 0.8 to 2.2 kg. during head immersion; effect of

Journal

AJP - Regulatory, Integrative and Comparative PhysiologyThe American Physiological Society

Published: Feb 1, 1983

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