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Vasopressin responses to unloading arterial baroreceptors during cardiac nerve blockade in conscious dogsWe examined the relative contributions of afferent input from the heart and from arterial baroreceptors in the stimulation of arginine vasopressin (AVP) secretion in response to hypotension caused by thoracic inferior vena caval constriction (TIVCC). Afferent input from cardiac receptors was reversibly blocked by infusing 2% procaine into the pericardial space to anesthetize the cardiac nerves. Acute cardiac nerve blockade (CNB) alone caused a rise in mean arterial pressure (MAP) of 24 +/- 3 mmHg but no change in plasma AVP. If the rise in MAP was prevented by TIVCC, plasma AVP increased by 39 +/- 15 pg/ml, and if MAP was allowed to increase and then was forced back to control by TIVCC, plasma AVP increased by 34 +/- 15 pg/ml. Thus the rise in MAP during CNB stimulated arterial baroreceptors, which in turn compensated for the loss of inhibitory input from cardiac receptors on AVP secretion. These results indicate that the maximum secretory response resulting from complete unloading of cardiac receptors at a normal MAP results in a mean increase in plasma AVP of 39 pg/ml in this group of dogs. When MAP was reduced 25% below control levels (from 95 +/- 5 to 69 +/- 3 mmHg) by TIVCC during pericardial saline infusion, plasma AVP increased by 79 +/- 42 pg/ml. However, the same degree of hypotension during CNB (MAP was reduced from 120 +/- 5 to 71 +/- 3 mmHg) led to a greater (P less than 0.05) increase in plasma AVP of 130 +/- 33 pg/ml. Because completely unloading cardiac receptors can account for an increase of only 39 pg/ml on average in this group of dogs, the remainder of the increase in plasma AVP must be due to other sources of stimulation. We suggest that the principal stimulus to AVP secretion after acute CNB in these studies arises from unloading the arterial baroreceptors.
Document ID
20050000805
Acquisition Source
Ames Research Center
Document Type
Reprint (Version printed in journal)
Authors
O'Donnell, C. P.
(School of Medicine, University of California San Francisco 94143)
Keil, L. C.
Thrasher, T. N.
Date Acquired
August 22, 2013
Publication Date
January 1, 1992
Publication Information
Publication: The American journal of physiology
Volume: 262
Issue: 1 Pt 2
ISSN: 0002-9513
Subject Category
Life Sciences (General)
Funding Number(s)
CONTRACT_GRANT: HL-41313
Distribution Limits
Public
Copyright
Other
Keywords
NASA Center ARC
NASA Discipline Cardiopulmonary

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