Document Detail


Effect of hematocrit on systemic O2 transport in hypoxic and normoxic exercise in rats.
MedLine Citation:
PMID:  7836138     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The effect of hematocrit (Hct) on O2 transport in hypoxic [inspired PO2 (PIO2) approximately 70 Torr] and normoxic (PIO2 approximately 145 Torr) exercise was studied in rats acclimatized to 3 wk of PIO2 at approximately 70 Torr (A rats) and in nonacclimatized littermates (NA rats). Isovolumic exchange transfusion of plasma or red blood cells was used to lower Hct in A rats from approximately 60 to 45% and to raise Hct of NA rats from 45 to 60%: Controls were A and NA rats exchange transfused with whole blood at constant Hct. Lowering Hct of A rats lowered the arterial O2 concentration (CaO2) and the arterial-mixed venous O2 difference and increased the maximal cardiac output (Qmax) without changes in maximal O2 uptake (VO2 max) or in the product of Qmax x CaO2, circulatory O2 convection at maximal exercise (TO2 max). Raising Hct in NA rats produced the opposite changes in CaO2, arterial-mixed venous O2 difference, and Qmax, but VO2 max and TO2 max increased significantly, both in hypoxia and normoxia, because of relatively small changes in Qmax. In NA rats, a steeper slope of the line relating VO2 max to calculated mean capillary PO2 at high Hct suggested a higher tissue O2 diffusing capacity with high Hct. For a given Hct and Qmax, systemic arterial pressure was higher in A rats. The data suggest that 1) the effect of Hct on systemic hemodynamics is different in A and NA rats, resulting in different effects on VO2 max; 2) factors in addition to Hct contribute to the high systemic vascular resistance of A rats; and 3) increased diffusive conductance for O2, as well as increased TO2 max, could be responsible for the effect of Hct on VO2 max of NA rats.
Authors:
N C Gonzalez; L P Erwig; C F Painter; R L Clancy; P D Wagner
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Journal of applied physiology (Bethesda, Md. : 1985)     Volume:  77     ISSN:  8750-7587     ISO Abbreviation:  J. Appl. Physiol.     Publication Date:  1994 Sep 
Date Detail:
Created Date:  1995-02-28     Completed Date:  1995-02-28     Revised Date:  2013-09-26    
Medline Journal Info:
Nlm Unique ID:  8502536     Medline TA:  J Appl Physiol (1985)     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  1341-8     Citation Subset:  IM; S    
Affiliation:
Department of Physiology, University of Kansas Medical Center, Kansas City 66160-7401.
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MeSH Terms
Descriptor/Qualifier:
Acclimatization / physiology
Acid-Base Equilibrium / physiology
Animals
Anoxia / blood*,  metabolism,  physiopathology
Cardiac Output / physiology
Hematocrit*
Male
Oxygen / blood*
Oxygen Consumption
Physical Exertion / physiology*
Pulmonary Diffusing Capacity / physiology
Pulmonary Gas Exchange / physiology
Rats
Rats, Sprague-Dawley
Grant Support
ID/Acronym/Agency:
HL-17731/HL/NHLBI NIH HHS; HL-39443/HL/NHLBI NIH HHS
Chemical
Reg. No./Substance:
7782-44-7/Oxygen

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


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