Haemodynamic changes in partial unilateral ureteric obstruction (PUUO) may be related to altered prostaglandin synthesis. In 12 dogs the left ureter was partially obstructed for 5 weeks. In six dogs the ureter was reimplanted into the bladder and to investigate the effect of this procedure on the contralateral side the other six animals underwent ipsilateral nephroureterectomy. Renal blood flow (RBF) was measured by the distribution of radiolabelled microspheres. Changes in urinary prostaglandin (PG) concentrations were validated by renin activity using angiotensin I. Reduced left RBF during obstruction was associated with increased thromboxane A2 synthesis (P < 0.01). Increased RBF to the non-obstructed side was associated with elevated PGE2 formation (P < 0.05). Elevated angiotensin I levels (P < 0.01) corresponded to maximal increases in PG synthesis. Reimplantation of the obstructed kidney did not exert a direct effect on contralateral RBF or PG concentration. Haemodynamic changes in PUUO in vivo are associated with alterations in renal PGs.

Complete unilateral ureteric obstruction decreases ipsi-lateral and increases contra-lateral renal blood flow, with shunting of intrarenal blood flow from outer to inner cortical zones. We tested the hypothesis that partial unilateral ureteric obstruction would also result in alterations in renal perfusion patterns. In five dogs, the left ureter was partially obstructed for 4 weeks and then reimplanted into the bladder for a further 4 weeks. Whitaker tests confirmed partial ureteric obstruction. Renal blood flow was assessed at each stage by distribution of radioactively labelled microspheres prior to and following ureteric obstruction and after reimplantation. Partial unilateral ureteric obstruction significantly decreased total blood flow to the ipsi-lateral kidney (51% vs 26%;P<0.05) and increases total blood flow to the contralateral kidney (49% vs 74%;P<0.05). In the ipsilateral kidney, partial ureteric obstruction induced a significant decrease in outer cortical blood flow (57% vs 76%;P<0.01) and a concomitant increase in inner cortical blood flow (35% vs 18%;P<0.02). A similar, albeit less marked, shunting of blood from outer to inner cortex was seen in the contralateral kidney. Relief of sbstruction after 4 weeks did not restore the renal circulation to its pre-obstruction profile. We speculate that the alterations in intrarenal blood flow may be hormonally mediated.