[The long-term effects of a new converting enzyme inhibitor, delapril hydrochloride, on renal function, renin-angiotensin-aldosterone system and kallikrein-kinin prostaglandin system in hypertensive patients].

The effects of a new angiotensin converting enzyme inhibitor, delapril hydrochloride, (delapril) on renal function, and the renin-angiotensin-aldosterone and kallikrein-kinin prostaglandin systems were studied in 10 hypertensive patients. After 4 to 12 months (7.6 +/- 0.9 [SE]) of treatment with 15-60 mg/day (36 +/- 6.8) of delapril (b.i.d.), mean arterial pressure was decreased from 126 +/- 3.0 to 110 +/- 4.4 mmHg (p less than 0.01). Although renal blood flow (RBF), assessed by PAH clearance and hematocrit, was increased from 437 +/- 51 to 490 +/- 49 ml/min (p less than 0.05) and renal vascular resistance was decreased (p less than 0.05), glomerular filtration rate, measured by endogenous creatinine clearance, did not change significantly. Thus, filtration fraction was reduced (p less than 0.01). Plasma renin activity was increased from 1.5 +/- 0.3 to 4.4 +/- 1.1 ng/ml/hr (p less than 0.01). Plasma aldosterone concentration tended to decrease (p less than 0.1), and urinary aldosterone excretion showed on significant change. Although urinary kallikrein and prostaglandin E2 excretions were increased (p less than 0.05), urinary thromboxane B2 excretions was reduced (p less than 0.05). In addition, the changes in RBF were significantly correlated with those in urinary PGE2 excretion (r = 0.63, p less than 0.05). These results suggest that the antihypertensive effect of delapril is multifactorial and that the improvement of RBF seen during delapril administration in the present study may be partly due to the suppression of the renin-angiotensin-aldosterone system and the activation of kallikrein-kinin-prostaglandin system.