Oxygen consumption by vascular wall in skeletal muscle arterioles under physiological conditions

To examine the large drop of partial oxygen pressure (PO₂) in arterioles, the O₂ consumption rates of arteriolar walls were determined under physiological conditions. A phosphorescence quenching technique was used to quantify the intra- and perivascular PO₂ values in rat cremaster arterioles. Using the measured PO₂ values, and a theoretical model, the O₂ consumption rates of the arteriolar walls were then estimated. We found that the O₂ consumption rate of arterioles was 100 times greater than that seen in in vitro experiments, and the O₂ consumption rate under normal conditions was significantly higher than that during vasodilation. Furthermore, the O₂ consumption rate was the highest in the upstream arterioles. These findings suggest that the high O₂ consumption rates of arteriolar walls depend on the workload of the smooth muscle.