Species-specific binding of vWf to human or canine platelets.

(A) Specific binding of ¹²⁵I-labeled vWf (1 μg/mL) to washed human or canine platelets (5 × 10⁷) in the presence of either ristocetin (1 mg/mL final concentration) or botrocetin (2.5 μg/mL final concentration) for 30 minutes at 22°C. Nonspecific binding was determined in the absence of modulator in a parallel assay. Data are the means of triplicate determinations (± SEM) and are representative of 3 separate experiments with different populations of cells. (B) Botrocetin-dependent binding of ¹²⁵I-labeled vWf (1 μg/mL) to washed human or canine platelets (5 × 10⁸/mL). Platelets were pretreated with TS buffer only or with 10 μg/mL mocarhagin (MOC) for 30 minutes at 22°C, washed once in TS buffer, and resuspended to the original concentration.