Hemoglobin oxygen saturation in the dog kidney.

Abstract

AbstractBlood from the various zones of the intact kidney of anesthetized dogs was collected by puncture with glass capillaries, and hemoglobin oxygen saturation percentage (% HbO2) determined spectrophotometrically. The mean values of 93 samples in 7 dogs from the renal cortex, outer and inner medullary zone, respectively, were: 68, 65 and 45% HbO2 during air respiration and 83, 71 and 47% HbO2 during oxygen respiration. The mean cortical % HbO2 was found to be 4% HbO2 lower than renal venous HbO2. The mean urine oxygen tension during air respiration was 23 mm Hg and during oxygen respiration 33 mm Hg. No correlation could be demonstrated between inner medullary HbO2 and corresponding urine pO2. It is concluded, however, that the low HbO2 in the inner medulla supports the hypothesis that urine pO2 is determined in the inner medulla by equilibration across the walls of the collecting ducts. The slight influence of oxygen respiration on inner medullary HbO2 may be due to a counter‐current effect of the vasa recta.