Factor VIII and vWF levels pre- and post-vWF infusion. Plasma samples were isolated at the indicated periods of time from a vWF-deficient pig. The times that vWF infusions were performed are indicated by the “I” arrows. vWF ristocetin cofactor activity and antigen and factor VIII activity were measured as described in Materials and Methods and presented as a percent of normal porcine values. Liver biopsies were performed at the times indicated by the “B” arrows. Factor VIII, □; Ristocetin cofactor, •; vWF antigen, ▴.