Effect of Thromboxane and Nitric Oxide Blockade on Renal Blood Flow Increase during Volume Expansion in Hydronephrotic Rats

Abstract

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

• Experimental Hydronephrosis Nitric Oxide Renal Blood Flow Thromboxane Ureteric Obstruction