Incorporating O2-Hb reaction kinetics and the Fåhraeus effect into a microcirculatory O2-CO2 transport model.
The influence of O2-Hb reaction kinetics and the Fåhraeus effect on steady state O2 and CO2 transport in cat brain microcirculation was investigated using our refined multicompartmental model. The most important model predictions include: 1) capillaries are the sites in the microcirculation where the effect of O2-Hb kinetics is most pronounced; 2) while there is only a small difference between equilibrium and actual oxygen saturation, this effect is not negligible; 3) O2-Hb kinetics tends to make the PO2 level at the venous entrance higher than in venules; 4) the influence of the Fåhraeus effect leads to a lower tissue PO2 level than in venules and the outlet vein. The resultant decline in tissue PO2 may lead to a decrease in O2 consumption rate and extraction ratio; 5) although the Fåhraeus effect changes the ratio between arteriolar flux and capillary flux, incorporating the Fåhraeus effect and O2-Hb kinetics into the simulation does not change our previous conclusion, that most of the O2 and CO2 exchange takes place at the capillary level; 6) in general, influences of O2-Hb kinetics and Fåhraeus effect are synergistic; 7) a model that excludes these two mechanisms might overestimate the tissue oxygenation level especially during severe hypoxia.
Ye
G F
GF
New Concept Development Division, Redwood City, CA 94063, USA. yegf@hotmail.com
Park
J W
JW
Basude
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R
Buerk
D G
DG
Jaron
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D000465:Algorithms; D000818:Animals; D001160:Arterioles / Q000502:physiology; D001692:Biological Transport; D002196:Capillaries / Q000502:physiology; D002245:Carbon Dioxide / Q000378:metabolism*; D002415:Cats; D002560:Cerebrovascular Circulation / Q000502:physiology*; D004058:Diffusion; D006454:Hemoglobins / Q000378:metabolism*; D008955:Models, Cardiovascular; D008959:Models, Neurological; D010101:Oxygen Consumption / Q000502:physiology*; D014699:Venules / Q000502:physiology
D006454:Hemoglobins; D002245:Carbon Dioxide