THE EFFECT OF ANGIOTENSIN-CONVERTING ENZYME-INHIBITION AND ANGIOTENSIN-II RECEPTOR ANTAGONISM ON OBSTRUCTED RAT BLADDER

Purpose: Others have demonstrated that inhibition of angiotensin II pr oduction partially ameliorates obstructive changes in the neonatal rab bit bladder. We examined the effect of angiotensin II converting enzym e inhibition and receptor antagonism on the obstructed rat bladder. Ma terials and Methods: Three groups of animals were investigated. Partia l bladder neck obstruction was created in 23 rats by placing a 2-zero silk ligature around the vesicourethral junction. Eight rats were give n untreated tap water, 9 were given water supplemented with 50 mg./kg. of the angiotensin-converting enzyme inhibitor captopril and 6 were g iven water with 30 mg./kg. of the angiotensin II subtype AT1 receptor antagonist losartan potassium. Eight unobstructed rats served as contr ols. After 2 weeks of partial outlet obstruction the animals were sacr ificed and bladders were harvested. Routine histological evaluation an d assays for total protein, deoxyribonucleic acid, and collagen conten t were performed; Results: Histological evaluation revealed that admin istration of captopril or losartan potassium resulted in a mild decrea se in the degree of obstructive bladder changes. Biochemically neither captopril nor losartan potassium caused a significant decrease in the amount of total deoxyribonucleic acid, protein or collagen content pe r bladder compared to untreated obstructed bladders. Conclusions: In c ontrast to previous studies in neonatal rabbits, neither captopril nor losartan potassium significantly ameliorated tile histological or bio chemical features of partial bladder outlet: obstruction in the rat. F urther investigation is necessary into species specific differences to understand better the role that angiotensin II may have in mediating the bladder changes of experimentally induced obstruction.