DELETERIOUS EFFECTS OF INHIBITION OF THE RENIN-ANGIOTENSIN SYSTEM IN NEONATAL RATS

The angiotensin I converting enzyme inhibitor (ACEI) perindopril (2 mg /kg body weight), the peripheral vasodilator dihydralazine (DHL) (25 m g/kg body weight) or distilled water was given daily from birth to day 14 to neonatal rats. Blood pressure, plasma creatinine, plasma renin activity (PRA), substrate (PRS) and concentration (PRC) and renin cont ent of kidney tissue sections were evaluated on days 14 and 28. By day 14, a high mortality in the ACEI group was observed. ACEI, but not DH L, led to a significant fall (P < 0.01) in blood pressure, 57 +/- 11 v ersus 89 +/- 25 in the DHL group and 103 +/- 24 mmHg in controls, and to a dramatic increase in plasma creatinine. PRA and PRS were undetect able in ACEI-treated rats; in contrast, PRC and renal staining with an ti-renin antibody were significantly increased in ACEI rats. On day 28 , the blood pressure was normal in all groups and plasma creatinine re turned to the normal range in ACEI rats. PRA, PRS and PRC were not sig nificantly different in the ACEI group and controls. These results sug gest that the renin-angiotensin system (RAS) plays a major postnatal r ole in the neonatal rat. Inhibition of the RAS during the first 2 week s of life leads to high mortality, severe hypotension, reversible rena l failure and a defect in circulating angiotensinogen.