VELOCITY DIFFERENCES BETWEEN L-SELECTIN-DEPENDENT AND P-SELECTIN-DEPENDENT NEUTROPHIL ROLLING IN VENULES OF MOUSE CREMASTER MUSCLE IN-VIVO

After surgical trauma, leukocyte rolling is initially normal in L-sele ctin-deficient mice and reduced at later times, whereas leukocyte roll ing is initially absent in P-selectin-deficient mice but induced later . Here, we examined the possibility that P- and L-selectin support foi ling at different characteristic velocities using intravital microscop y of venules of the exteriorized cremaster muscle venules of wild type (WT) and P- and L-selectin-deficient mice. At >50 min after exteriori zation, rolling in P-selectin-deficient mice occurred at significantly higher velocities (129 +/- 89 mu m/s) than in WT mice (49 +/- 23 mu m /s). Rolling velocity distribution in L-selectin-deficient mice was si milar to WT mice immediately after exteriorization. Histological exami nation of Giemsa-stained whole-mount preparations in cremaster muscle venules revealed that the majority of rolling cells (similar to 90% in all genotypes) were granulocytes. We conclude that P-selectin mediate s leukocyte rolling at velocities <50 mu m/s, whereas L-selectin susta ins more rapid rolling. Under physiological conditions, P- and L-selec tin synergize to support rolling at velocities between 20 and 70 mu m/ s as seen in WT mice.