Oxygen transport across vasa recta in the renal medulla
W Zhang, A Edwards - American Journal of Physiology …, 2002 - journals.physiology.org
W Zhang, A Edwards
American Journal of Physiology-Heart and Circulatory Physiology, 2002•journals.physiology.orgIn this model of oxygen transport in the renal medullary microcirculation, we predicted that
the net amount of oxygen reabsorbed from vasa recta into the interstitium is on the order of
10− 6 mmol/s, ie, significantly lower than estimated medullary oxygen requirements based
on active sodium reabsorption. Our simulations confirmed a number of experimental
findings. Low medullary Po 2results from the countercurrent arrangement of vessels and an
elevated vasa recta permeability to oxygen, as well as high metabolic needs. Diffusional …
the net amount of oxygen reabsorbed from vasa recta into the interstitium is on the order of
10− 6 mmol/s, ie, significantly lower than estimated medullary oxygen requirements based
on active sodium reabsorption. Our simulations confirmed a number of experimental
findings. Low medullary Po 2results from the countercurrent arrangement of vessels and an
elevated vasa recta permeability to oxygen, as well as high metabolic needs. Diffusional …
In this model of oxygen transport in the renal medullary microcirculation, we predicted that the net amount of oxygen reabsorbed from vasa recta into the interstitium is on the order of 10−6 mmol/s, i.e., significantly lower than estimated medullary oxygen requirements based on active sodium reabsorption. Our simulations confirmed a number of experimental findings. Low medullary Po 2results from the countercurrent arrangement of vessels and an elevated vasa recta permeability to oxygen, as well as high metabolic needs. Diffusional shunting of oxygen between descending vasa recta (DVR) and ascending vasa recta also explains why a 20-mmHg decrease in initial Po 2 at the corticomedullary junction only leads to a small drop in papillary tip Po 2 (<2 mmHg with baseline parameter values). Conversely, small changes in the consumption rate of DVR-supplied oxygen, in blood flow rate, in hematocrit, or in capillary permeability to oxygen, beyond certain values sharply reduce interstitial Po 2. Without erythrocytes, papillary tip Po 2 cannot be maintained above 10 mmHg, even when oxygen consumption is zero.
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