Onset and duration of antithrombotic activity. HCII^+/+ mice were given porcine skin dermatan sulfate at a dose of 10 mg/kg (•) or 20 mg/kg (○), or an equal volume of 0.15 M NaCl (□), by intravenous injection at time = 0 minute. At specified intervals thereafter, vascular injury was initiated by injection of rose bengal, and the time to thrombotic occlusion was determined. Error bars represent the mean ± SD. Numbers in parentheses indicate the number of mice studied. P values indicate statistical significance relative to mice that did not receive dermatan sulfate: ^*P < .0001; †P = .068; and ‡P = .28.