PRINCIPLES DETERMINING THE TRANSPORT OF O XYGEN THROUGH THE WALLS OF VEINS

Objective To review the mechanisms of oxygen transport in the walls of arteries and veins and to consider whether oxygen transport might lim it oxygen consumption in the venous wall. Methods (i) To review eviden ce for the contributions of transport from the vascular lumen and tran sport from the vasa. vasorum to the supply of oxygen to the walls of a rteries. (ii) To use the general principles of oxygen diffusion throug h tissues to extrapolate the findings of investigations of oxygen tran sport into arterial walls to transport into the walls of the larger ve ins. Results and Discussion The magnitude of oxygen transport from the vessel lumen into the vessel wall is dependent on the partial pressur e of oxygen (PO2) in the vessel lumen. While luminal PO2 is constant a nd high in arteries, it is a physiological variable in veins of health y people. In larger veins, there is evidence that flow in the vasa vas orum increases as PO2 in the vessel lumen falls. The extent to which t his regulatory action of the vasa vasorum may be comprised by raised v enous pressure and venous distension has not been defined.