Figure 2. Reversal of heparin-induced increases in Kaolin-(left) and Celite-(right) activated clotting time by protamine and various doses of heparinase I (Neutralase). Heparin (300 units/kg, intravenous) was injected at -10 min, whereas heparinase I, vehicle of heparinase I (0.125 ml/kg, a volume equivalent to 2.5 IU/kg) or protamine (3.9 mg/kg) was injected intravenously at 0 min. Results are presented as mean+/- SD. *P < 0.05, **P < 0.01, compared to the vehicle group. All heparinase I-treated and protamine-treated groups are statistically similar.