Effect of renin inhibitor, ES-8891, on renal renin secretion and storage in the marmoset: comparison with captopril.

We investigated the effects of the human renin inhibitor, ES-8891, and captopril on renal renin secretion and storage in the marmoset. Either ES-8891 (30 mg/kg) or captopril (2 mg/kg) was given orally twice a day for 1 week to conscious, sodium-depleted marmosets (n = 6 for each group). The ES-8891-treated group displayed a significant reduction in mean arterial pressure (MAP), plasma renin activity (PRA) and plasma immunoreactive renin (PIR) compared with the control group. Kidney renin content was significantly increased compared with the control group and enlarged renin granules containing heterogenous internum were observed in juxtaglomerular cells after treatment with ES-8891. Treatment with captopril significantly increased PRA and PIR compared with the control day as well as increasing kidney renin content and the number of renin granules with crystalline content in juxtaglomerular cells compared with the control group. These results suggest that ES-8891 inhibits both PRA and renin secretion from the kidney, resulting in an increase in renal renin storage.