Effect of Thromboxane Inhibition on Renal Blood Flow in Dogs with Complete Unilateral Ureteral Obstruction

Abstract The effect of the thromboxane synthetase inhibitior OKY-046 on renal blood flow and ureteral pressure in awake dogs during 18 hours of complete unilateral ureteral obstruction was studied. OKY-046 was infused continuously throughout the period of obstruction and post-release. Renal blood flow and ureteral pressure were constantly monitored during the study. Urinary thromboxane B 2 and prostaglandin E 2 excretion served as markers for inhibition of renal thromboxane A 2 synthesis. The triphasic relationship between ipsilateral renal blood flow and ureteral pressure previously found following unilateral ureteral obstruction was observed despite OKY-046 infusion. Inhibition of ipsilateral urinary thromboxane B 2 excretion was greater than 90% compared to control while ipsilateral urinary prostaglandin E 2 excretion was not consistently decreased showing specific thromboxane inhibition. These results suggest that urinary thromboxane B 2 may serve as a useful marker for determining the effects of inhibition on renal thromboxane A 2 production. At the level of inhibition of thromboxane synthesis achieved we did not observe any change in the late decrease in renal blood flow which is typically seen with chronic unilateral ureteral obstruction.