Effect of thromboxane and nitric oxide blockade on renal blood flow increase during volume expansion in...

It has recently been found that hydronephrotic rats, despite low diuresis, show a significant increase in renal blood flow (RBF) during volume expansion. The present experiments were designed to evaluate the mechanisms underlying this phenomenon.

Three-week-old Sprague-Dawley rats underwent partial obstruction of the left ureter using the Ulm-Miller psoas groove technique. The effects on RBF were studied 3 weeks later under general anesthesia using real-time ultrasound flowmetry, first during normohydration and then during extracellular volume expansion, in both untreated animals, and after prior blockade of either thromboxane or nitric oxide.

Significant hydronephrosis developed in all cases. RBF was normal under control conditions. During volume expansion RBF increased significantly in untreated experimental animals (mean 7.5%). In contrast to this finding, RBF remained unchanged during volume expansion in both the thromboxane and nitric oxide blockade groups.

It is concluded that a thromboxane- and/or nitric oxide-dependent RBF redistribution takes place in hydronephrotic kidneys during volume expansion.