Document Detail

Blood transit time heterogeneity is associated to oxygen extraction in exercising human skeletal muscle.
MedLine Citation:
PMID:  15020203     Owner:  NLM     Status:  MEDLINE    
Capillary transit time and its heterogeneity have a marked impact on oxygen extraction in different tissues. Animal studies have shown that exercise shortens capillary transit time but the effects on capillary transit time heterogeneity have been controversial. We investigated whether exercise changes muscle blood transit time heterogeneity in humans in vivo and whether this heterogeneity correlates to muscle oxygen extraction. Muscle blood flow, blood volume, and oxygen uptake were measured during rest and low-intensity exercise in 12 healthy men using positron emission tomography (PET). Blood transit time was calculated from parametric PET images voxel by voxel by dividing blood volume with blood flow. Oxygen extraction was calculated by nonlinear fitting from dynamic 15O-O2 data. Relative dispersion (=SD/mean) was calculated as an index of heterogeneity of blood volume and blood transit time. As expected, exercise significantly shortened blood transit time and increased oxygen extraction. Furthermore, exercise decreased transit time heterogeneity (from 47 +/- 9% to 39 +/- 10%, P=0.07). Transit time heterogeneity correlated inversely to oxygen extraction in the exercising (r=-0.76, P=0.004) but not in the resting muscle (r=0.04, P=0.89). These results show that even low-intensity exercise shortens blood transit time markedly and decreases its heterogeneity in human skeletal muscle in vivo. Findings in correlation analyses suggest that less heterogeneous blood transit time associates to better muscle oxygen extraction during exercise. This may have effects on muscle oxygenation during exercise.
Kari K Kalliokoski; Juhani Knuuti; Pirjo Nuutila
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Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Microvascular research     Volume:  67     ISSN:  0026-2862     ISO Abbreviation:  Microvasc. Res.     Publication Date:  2004 Mar 
Date Detail:
Created Date:  2004-03-15     Completed Date:  2004-12-07     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0165035     Medline TA:  Microvasc Res     Country:  United States    
Other Details:
Languages:  eng     Pagination:  125-32     Citation Subset:  IM    
Turku PET Centre, University of Turku, Turku, Finland.
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MeSH Terms
Blood Flow Velocity*
Exercise / physiology*
Muscle, Skeletal / blood supply*,  metabolism,  radionuclide imaging
Oxygen Consumption
Physical Endurance
Positron-Emission Tomography

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