The in vivo effect of RAP infusion in hPF4^High and mPF4^−/− animals. Both hPF4^High mice (left) and mPF4^−/− mice (right) were treated with approximately 800 μg/kg per day by continuous 7-day infusion of RAP or PBS diluent using an Alzet osmotic pump. Mice receiving only PBS are shown as □ and those receiving a RAP infusion are shown as . For hPF4^High mice, 10 animals were studied per arm and for the mPF4^−/− mice, 5 per arm. *P < .02 versus PBS-treated animals on days 5 and 7 after pump placement. represents time of RAP infusion.