Inhibition of plasma ACE activity by perindopril in mice irradiated with 8.3 Gy. Blood samples were collected from control and irradiated mice before administration of water or perindopril 1 hour after the first administration (A1), 1 hour after the injection on day 2 (A2), and on day 3, 12 hours after the last administration (A3). ACE activity was measured. Results are expressed as the percentage of ACE inhibition compared with water-treated controls. • indicates water-treated nonirradiated mice; ▴, water-treated irradiated mice; ▴, irradiated mice treated with 10 mg/kg perindopril; ▵, irradiated mice treated with 30 mg/kg perindopril; and ▪, irradiated mice treated with 90 mg/kg perindopril. All irradiated mice received a single dose of 7 Gy. Error bars indicate standard deviation.