EFFECT OF EXPERIMENTALLY-INDUCED URETHRAL OBSTRUCTION AND SURGICAL DECOMPRESSION IN-UTERO ON RENAL DEVELOPMENT AND FUNCTION IN RABBITS

To investigate the effect of urethral obstruction during late fetal li fe on renal development and function, we developed a rabbit fetal mode l of obstructive nephropathy to examine the pathological and biochemic al consequences of urethral obstruction and beneficial effects of earl y surgical decompression. Animals were divided into four groups, i.e., obstructed, early decompressed, late decompressed, and control. Fetal renal development was evaluated by histological examination and count ing the number of glomeruli in the four groups. The number of renal gl omeruli correlated with gestational age in the normal fetus (r = 0.90, P < 0.0001). Urethral ligation on gestational day 25 (full-term, 31 d ays) resulted in thinning of the renal cortex and significantly decrea sed the number of renal glomeruli. The concentration of urinary microa lbumin was higher when urethral obstruction was maintained for 3 days than 1 day after urethral obstruction, although urinary beta(2)- micro globulin, Na, Cl, and osmotic pressure did not change during this peri od. Decompression of urethral obstruction 1 day after induction of ure thral obstruction resulted in improvement in the severity glomerular h ypoplasia compared with late decompression (P < 0.01). Our results sug gest that the rabbit fetal model simulates fetal urethral obstruction in humans, and indicates that early surgical decompression may be effe ctive in restoration of normal renal function. (C) 1998 Elsevier Scien ce Ireland Ltd. All rights reserved.