Lifetime treatment with captopril improves renal function in spontaneouslyhypertensive rats.

Lifetime treatment with captopril prevents the development of hypertension in spontaneously hypertensive rats (SI-IR). This study tests the hypothesis that compared to untreated hypertensive SHR, captopril-treated SHR display similar diuretic and natriuretic responses to an isotonic saline infusion despite significantly lower arterial pressure. Eight-week-old, male SHR wer e instrumented with femoral arterial, venous, and bladder catheters. Forty- eight hours later, each rat was infused intravenously with an isotonic sali ne load (5% of body weight; 0.5 ml/min). Lifetime captopril-treated SHR and untreated control SHR displayed nearly identical natriuretic and diuretic responses to the saline infusion. Thus, although lifetime captopril treatme nt significantly reduces mean arterial pressure in SHR, renal excretory res ponses appear to be unaltered. Moreover, histological examination of the ki dneys of the lifetime captopril-treated SHR did not reveal significant stru ctural damage in the kidneys at either 8 weeks of age or at 12 months of ag e. Together, the data suggest that lifetime captopril treatment does not ad versely affect renal function and structure in SHR.