Resting platelets adhere to vWF in activated mesenteric venules.

Topical superfusion of A23187 on mesenteric venules induced the same platelet adhesion in WT (▪) and P−/− mice (○), n = 5 and n = 7, respectively. This process was absent in vWF−/− mice (, n = 10, P < .001 vs WT mice for 6 minutes after A23187treatment). Values were determined on a 250-μm long, 150-μm wide vessel segment and were translated as the number of adherent fluorescent platelets/mm²·frame (see “Materials and methods”).