Effect of acute changes in renal arterial blood flow on urine oxygen tension in dogs.

The relationships between urine oxygen tension (PuO2), PaO2, and acute changes in renal arterial blood flow (RBF) were studied in 19 anesthetized dogs. Indwelling sensors that measure continuously PO2 were inserted into the femoral artery and the ureter. RBF was measured by an electromagnetic flowmeter placed over the renal artery. PuO2 increased significantly from 36 to 72 torr during a stepwise increase in PaO2 from 70 to 180 torr. RBF was decreased in a stepwise fashion from a baseline value of 5.51 to 4.16, 2.13, and finally to .20 ml/kg.min by aortic constriction. PuO2 decreased significantly from a baseline value of 72 torr to 66, 57, and finally to 23 torr. The correlation coefficient between RBF and PuO2 was .84, which was significantly higher than that between RBF and femoral arterial pressure or that between RBF and urinary flow rate. This study demonstrates that PuO2 is a sensitive indicator of acute RBF changes in normal, healthy dogs.