Renal perfusion and intratubular pressure during ureteral occlusion in the rat

To define the interrelationship between changes in total renal blood flow (TRBF) and proximal tubular hydrostatic pressure (PTP), rats were studied 2, 3, 4, 6, 12, 18, and 24 h after bilateral ureteral occlusion (BUO). In control animals, a peak rise in both TRBF (3.52 +/- 0.26 ml . min-1 . 100 g body wt-1 . kidney-1) and PTP (28.6 +/- 1.3 mmHg) occurred 3 h after BUO. At each subsequent time interval, both TRBF and PTP fell, so that by 24 h after BUO, TRBF was 1.53 +/- 0.34 and PTP was 16.5 +/- 0.6, while in sham-operated rats the values were 2.52 +/- 0.22 ml . min-1 . g body wt-1 . kidney-1 and 12.8 +/- 0.2 mmHg, respectively. In animals treated with indomethacin (10 mg/kg) at the time of BUO, the alterations in both TRBF and PTP were completely ameliorated. At 3 h, TRBF was 1.8 +/- 0.32 ml . min-1 . 100 g body wt-1 . kidney-1 and PTP was 15.3 +/- 1.0 mmHg. TRBF and PTP remained essentially unchanged at each subsequent time period. These data indicate that 1) alterations in TRBF and PTP follow a similar and parallel pattern during BUO; 2) the pattern of changes in TRBF and PTP can be eliminated by treatment with indomethacin; and 3) renal hemodynamics appear to be the dominant factor in producing these changes during the first 12 h after BUO, whereas a sustained increase in tubular hydrostatic pressure may play a primary role in decreasing TRBF 12-24 h after ureteral occlusion.