Document Detail

Hemodynamic effects of blood loss during a passive response to a stressor in the conscious rabbit.
MedLine Citation:
PMID:  14592929     Owner:  NLM     Status:  MEDLINE    
In the conscious rabbit, exposure to an air jet stressor increases arterial pressure, heart rate, and cardiac output. During hemorrhage, air jet exposure extends the blood loss necessary to produce hypotension. It is possible that this enhanced defense of arterial pressure is a general characteristic of stressors. However, some stressors such as oscillation (OSC), although they increase arterial pressure, do not change heart rate or cardiac output. The cardiovascular changes during OSC resemble those seen during freezing behavior. In the present study, our hypothesis was that, unlike air jet, OSC would not affect defense of arterial blood pressure during blood loss. Male New Zealand White rabbits were chronically prepared with arterial and venous catheters and Doppler flow probes. We removed venous blood until mean arterial pressure decreased to 40 mmHg. We repeated the experiment in each rabbit on separate days in the presence and absence (SHAM) of OSC. Compared with SHAM, OSC increased arterial pressure 14 +/- 1 mmHg, central venous pressure 3.3 +/- 0.4 mmHg, and hindquarter blood flow 34 +/- 4% while decreasing mesenteric conductance 32 +/- 3% and not changing heart rate or cardiac output. During normotensive hemorrhage, OSC enhanced hindquarter and renal vasoconstriction. Contrary to our hypothesis, OSC (23.5 +/- 0.6 ml/kg) increased the blood loss necessary to produce hypotension compared with SHAM (16.8 +/- 0.6 ml/kg). In nine rabbits, OSC prevented hypotension even after a blood loss of 27 ml/kg. Thus a stressful stimulus that resulted in cardiovascular changes similar to those seen during freezing behavior enhanced defense of arterial pressure during hemorrhage.
James C Schadt; Eileen M Hasser
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.     Date:  2003-10-30
Journal Detail:
Title:  American journal of physiology. Regulatory, integrative and comparative physiology     Volume:  286     ISSN:  0363-6119     ISO Abbreviation:  Am. J. Physiol. Regul. Integr. Comp. Physiol.     Publication Date:  2004 Feb 
Date Detail:
Created Date:  2004-01-06     Completed Date:  2004-02-27     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  100901230     Medline TA:  Am J Physiol Regul Integr Comp Physiol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  R373-80     Citation Subset:  IM    
Dalton Cardiovascular Research Center, Univ. of Missouri, Columbia, MO 65211, USA.
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MeSH Terms
Blood Pressure
Cardiac Output
Central Venous Pressure
Heart Rate
Hemorrhage / complications*,  physiopathology*
Hindlimb / blood supply
Hypotension / etiology,  prevention & control
Physical Stimulation
Regional Blood Flow
Splanchnic Circulation
Stress, Physiological / complications*
Time Factors

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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