Long-term effects of delapril on renal function and urinary excretion of kallikrein, prostaglandin E2, and thromboxane B2 in hypertensive patients. The effects of delapril, an angiotensin converting enzyme (ACE) inhibitor, on renal function and the renin-angiotensin and kallikrein-prostaglandin systems were investigated in 10 hypertensive patients who were treated for between 4 months and 1 year. There was a significant (P less than .05) increase in renal blood flow (RBF) without affecting glomerular filtration rate. Filtration fraction increased, while renal vascular resistance decreased. There were also significant (P less than .05) increases in urinary kallikrein and prostaglandin excretion, while thromboxane excretion decreased. There was no change in urinary aldosterone excretion. These results suggest that renal hemodynamic changes seen during long-term therapy with delapril are caused, in part, by activation of the kallikrein-prostaglandin system, as well as suppression of the renin-angiotensin system. 