The objectives of the current work are to place the important field of research on mathematical simulation of the microcirculation on the stronger base and to obtain direct experimental confirmation of the validity of the results. A simplified analysis has been completed which indicates that the resistance to oxygen transfer in the capillaries is much higher than previously reported. Numerical solutions of the partial differential equations of oxygen transport indicate the relative importance of the various parameters and show the need for careful treatment of the oxyhemoglobin diffusion and reaction kinetics expressions. It is proposed to carry out numerical solutions of the equations of oxygen transport in the cylindrical geometry for the ranges of the parameters of primary interest in the microcirculation. Additional approximate analyses will be carried out to estimate oxygen fluxes in the plasma, and to reduce the results of the numerical solutions to forms of practical utility. The experimental work will involve fabrication of 5 to 10 micron diameter capillaries of silicone rubber. Direct determination of hemoglobin saturation changes will be made in red cell suspensions flowing in the capillaries. Measurements of heme absorbance will be used to monitor oxygen transport over a wide range of conditions.

National Institute of Health (NIH)
National Heart, Lung, and Blood Institute (NHLBI)
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Surgery and Bioengineering Study Section (SB)
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Rice University
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United States
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Liu, C Y; Udden, M M; Hellums, J D (1995) Oxygen transport in thin layers of packed sickle erythrocytes. Microvasc Res 49:78-96
Huang, N S; Hellums, J D (1994) A theoretical model for gas transport and acid/base regulation by blood flowing in microvessels. Microvasc Res 48:364-88
Huang, N S; Hellums, J D; Olson, J S (1994) Mathematical simulation of gas transport and acid/base regulation by blood flowing in microvessels--the Cl-/HCO3-exchange across the red cell membrane. Adv Exp Med Biol 345:167-74
Nair, P K; Huang, N S; Hellums, J D et al. (1990) A simple model for prediction of oxygen transport rates by flowing blood in large capillaries. Microvasc Res 39:203-11
Nair, P K; Hellums, J D; Olson, J S (1989) Prediction of oxygen transport rates in blood flowing in large capillaries. Microvasc Res 38:269-85
Lemon, D D; Nair, P K; Boland, E J et al. (1987) Physiological factors affecting O2 transport by hemoglobin in an in vitro capillary system. J Appl Physiol 62:798-806
Yap, E W; Hellums, J D (1987) Use of Adair four-step kinetics in mathematical simulation of oxygen transport in the microcirculation. Adv Exp Med Biol 215:193-207
Boland, E J; Nair, P K; Lemon, D D et al. (1987) An in vitro capillary system for studies on microcirculatory O2 transport. J Appl Physiol 62:791-7
Stathopoulos, N A; Nair, P K; Hellums, J D (1987) Oxygen transport studies of normal and sickle red cell suspensions in artificial capillaries. Microvasc Res 34:200-10
Stathopoulos, N A; Hellums, J D (1986) Oxygen transport studies of normal and sickle erythrocyte suspensions in artificial capillaries. Adv Exp Med Biol 200:35-41

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