1. The renin inhibitory effect of 2-[4-(4′-chlorophenoxy)phenoxy - acetylamino]ethylphosphoryl - ethanolamine (PE-104) was examined both in vitro and in vivo.
2. PE-104 inhibited the rate of angiotensin formation from dog renin and renin substrate reaction. The Ki value was 2 mmol/l and the inhibition was competitive.
3. In normotensive rats, infusion of PE-104 abolished the increases of blood pressure and plasma angiotensin I concentration due to renin injection. In renal hypertensive rats, infusion of PE-104 decreased blood pressure and this was associated with a decrease of plasma angiotensin I concentration.
4. These observations confirm that PE-104 is a renin inhibitor.