Intravascular inhomogeneous oxygen distribution in microvessels: Theory

Cross-sectional oxygen distribution in microvessels in most previous studies has been assumed to be homogeneous. Recent studies using phosphorescence quenching microscopy or microspectrophotometry showed a decline in oxygen profile near the arterial wall. In this study we performed theoretical analysis of intravascular P_O2 and S_O2 profiles in arterioles by using a radial diffusion model with a constant oxygen efflux from the vascular lumen, taking intravascular flow distribution into account. Theoretical calculations indicated that radial oxygen diffusion and a laminar flow pattern would create inhomogeneous intravascular oxygen profile with a decline toward the arterial wall. As mean blood flow velocity became lower, the difference between the centerline oxygen level and the inner surface level became larger. In conclusion, it is suggested that oxygen efflux from the vascular lumen and less convective supply near the vascular wall create a decline in P_O2 as well as S_O2 toward the arterial wall.