Arterial Wall Oxygen Consumption Rate Varies Spatially

The ratio of the O2 consumption rate (Q) to the O2 transmissibility (diffusivity-solubility product, Dk) was estimated by curve-fitting O2 tension profiles measured in vascular strips in vitro and in blood vessels in vivo. For rabbit aortic tissue in vitro, Q/Dk was 2.51 +/- 0.28 (SE) X 10(5) Torr/cm2 (n = 9). For various dog vessels in vivo, Q/Dk ranged from 0.15 to 47 X 10(5) Torr/cm2. In most cases, Q/Dk was higher near the endothelium than in the outer wall. This difference appears to be caused by a higher Q. Computer simulations using a two-layer O2 transport model with estimated Q/Dk indicate that the O2 supply from the vasa vasorum is essential to prevent medial wall hypoxia.