Figure 1.

Characteristics of leukocyte rolling in vWf −/− venules stimulated by A23187. (A) The number of leukocytes rolling per min was observed by intravital microscopy in mesenteric venules of vWf +/+ (black bars), vWf −/− (gray bars), or P-selectin-deficient (white bars, too small to see) mice before and after superfusion with the calcium ionophore A23187 (n ≥ 6). There were fewer leukocytes rolling in the absence of vWf both before (P < 0.0001) and after (P < 0.0025) A23187. In P-selectin-deficient mice, rolling was undetectable. (B) Leukocyte velocity was measured in mesenteric veins of vWf +/+ (■) or vWf −/− (░⃞) mice before and after A23187 treatment. Leukocytes roll faster in vWf −/− mice after A23187 treatment (P < 0.0001 for all time points).