Impact of diffusional oxygen transport on oxidative metabolism in the heart.

The resistance for the oxygen molecule to diffuse from the capillary blood to the cell surface produces remarkably large gradients of oxygen partial pressure (PO2) in the extracellular space. In addition, the intracellular radial gradients of PO2 may not be ignored particularly when the cellular oxygen consumption is increased. These PO2 gradients together result in a quite low intracellular PO2 in the cardiomyocyte in vivo. Thus, the cellular oxidative metabolism may be limited by diffusional transport of oxygen from the capillary blood to mitochondria. In this review, quantitative aspects and physiological relevances of the PO2 gradient in the myocardium are discussed.