Renal blood flow after bilateral ureteral ligation in the rat.

Renal blood flow (RBF) in rat was measured by using a noncannulating electromagnetic flowmeter. In the sham control rats, anesthetized with Inactin, RBF averaged 7 ml/min/g KW when arterial blood pressure was above 110 mm Hg. Autoregulation of RBF was observed when the arterial blood pressure was in the range of 110-150 mm Hg. Glomerular filtration rate (GFR), measured by polyfructosan clearance, averaged 1.08 ml/min/g KW. In experimental rats with 24 h of bilateral ureteral ligation (BUL), RBF averaged 38% of control value. During 1/2-3 h following release of the left ureteral occlusion, RBF increased to 60% of control value. The autoregulatory ability of the damaged kidney was reduced during BUL and did not improve after releasing occlusion. During the post-obstructive period arterial blood pressure remained stable. Thus, a high total renal vascular resistance was responsible for the depressed RBF. GRF in these rats averaged only 9% of control value. The reduction in RBF alone does not explain the drastic reduction in GFR in this model of renal failure.