Defense Date

2021

Document Type

Thesis

Degree Name

Master of Science

Department

Physiology and Biophysics

First Advisor

Roland Pittman

Abstract

Oxygen transport from a capillary to skeletal muscle tissue is a complex process that involves convective and diffusive mechanisms to deliver adequate oxygen to meet tissue metabolic activities. Typically, oxygen uptake in tissue is set by oxygen demand, which is set by metabolic activity. The relationship between the oxygen consumption (VO2) of an isolated perfused tissue and the rate of delivery of oxygen (QO2) to the tissue has been a subject of interest to many investigators over the past century. Experiments have shown that there is a critical value of QO2 below which tissue VO2 begins to decline. The Michaelis-Menten kinetics model for oxygen-dependent oxygen consumption is investigated as a modeling assumption in a computational study of oxygen transport from capillaries to skeletal muscle tissue using the Krogh cylinder model. The work presented in this thesis extends Schumacker and Samsel’s computational model to include the more accurate Michaelis-Menten kinetic description of the oxygen tension (PO2) dependence of VO2, using the parameter km, the PO2 for half-maximal VO2. This study aims to predict the relationship between oxygen consumption and oxygen delivery by considering the oxygen transport processes at the microvascular level. The dependence of oxygen consumption on oxygen delivery, critical oxygen extraction, critical oxygen delivery, and tissue oxygen tension profiles were examined as a function of km. The critical oxygen delivery was found to depend on km, increasing nonlinearly as km increases. The fractional oxygen extraction at the critical QO2 varied inversely with km. The venous oxygen partial pressure (PvO2) also varied with km. Finally, the predicted radial profile of tissue oxygen tension at the critical QO2 depended on km. At lower critical oxygen delivery and at lower km, the critical radial distance at which tissue oxygen partial pressure was found to be km occurred closer to the end of the capillary. The present results suggest that the value of km influences the relationship between tissue oxygen consumption and oxygen supply as the oxygen delivery is reduced to the critical point. Ultimately, km becomes the fundamental parameter that specifies how oxygen consumption depends on oxygen tension instead of the critical mitochondrial oxygen tension.

Rights

© The Author

Is Part Of

VCU University Archives

Is Part Of

VCU Theses and Dissertations

Date of Submission

8-9-2021

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