CAPTOPRIL (AN INHIBITOR OF ANGIOTENSIN-CONVERTING ENZYME) INHIBITS OBSTRUCTIVE CHANGES IN THE NEONATAL RABBIT BLADDER

Objectives. To investigate whether angiotensin II has a role in the re gulation of bladder smooth muscle growth and function, we developed a model of bladder neck obstruction (BNO) in the neonatal rabbit and inv estigated the effect of captopril (angiotensin converting enzyme inhib itor) on the obstructive changes in the developing bladder. Methods, P artial BNO was induced in a group of 2-day-old rabbits (n = 8) by plac ing a loose 2-0 silk ligature around the vesicourethral junction. A se cond group of rabbits subjected to the identical partial BNO procedure (n = 8) was given captopril (I mg/kg/day). Twelve days postobstructio n, bladders from these animals, along with paired controls (n = 8), we re harvested and assayed for total protein, DNA, and collagen content. Results. Partial BNO resulted in a 170% increase in wet weight (P <0. 05), 132% increase in protein/deoxyribonucleic acid (DNA) ratio (P <0. 05), 75% increase in total DNA (P <0.05), and 115% increase in total c ollagen (P <0.05). When compared with obstructed animals, captopril ad ministration significantly inhibited the increase in total DNA (P <0.0 5) and reduced the amount of total collagen (P = 0.054). Examination o f histology specimens demonstrated that captopril inhibited the serosa l hyperplasia and collagen deposition associated with obstruction. Con clusions. These data demonstrate that captopril partially inhibits the changes in the neonatal rabbit bladder associated with obstruction, s upporting the hypothesis that angiotensin II is involved in the regula tion of bladder smooth muscle growth and collagen production. (C) 1997 , Elsevier Science Inc. All rights reserved.