Oxygen transport in striated muscle microcirculation: reconciliation of theory and experiment

The large discrepancy between the observed and expected diffusive loss of oxygen is studied. The measured diffusive flow of oxygen from arterioles is approximately an order of magnitude greater than expected from theoretical considerations. Theory and experiment could be reconciled if the Krogh coefficient for oxygen in the muscle were an order of magnitude greater than the value found by in vitro experiments. Measurements have been made under conditions that mimic those of in vivo microcirculatory experiments to determine whether the diffusion coefficient for oxygen in muscle is much higher than the previous in vitro value. Results indicate that this factor might be 10-20% higher than previously thought, but the increase is not enough to account for the disparity between theory and experiment. However, coupled with upward revisions of oxygen solubility in muscle by a factor of two, these data lead to a Krogh coefficient that is about two times higher than the previous value