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A Separate Role for ICAM‐1 and Fluid Shear in Regulating Leukocyte Interactions with Straight Regions of Venular Wall and Venular Convergences
Author(s) -
SUMAGIN RONEN,
LAMKINKENNARD KATHLEEN A.,
SARELIUS INGRID H.
Publication year - 2009
Publication title -
microcirculation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.793
H-Index - 83
eISSN - 1549-8719
pISSN - 1073-9688
DOI - 10.1080/10739680902942271
Subject(s) - biophysics , chemistry , shear (geology) , microbiology and biotechnology , materials science , biology , composite material
Objective: Variation in expression of adhesion molecules plays a key role in regulating leukocyte behavior, but the contribution of fluid shear to these interactions cannot be ignored. Here, we dissected the effects of each of these factors on leukocyte behavior in different venular regions. Materials and Methods: Leukocyte behavior was quantified in blood‐perfused microvascular networks in anesthetized mouse cremaster muscle, using intravital confocal microscopy. ICAM‐1 expression and fluid shear rate were quantified by using ICAM‐1 fluorescent labeling, fluorescent particle tracking, and computational fluid dynamics. Results: Tumor necrosis factor alpha induced an increase in ICAM‐1 expression and abolished the differences observed among control venules of different sizes. Consequently, leukocyte adhesion was increased to a similar level across all vessel sizes [5.1±0.46 leukocytes/100 μm vs. 2.1±0.47 (control)], but remained significantly higher in venular convergences (7.8±0.4). Leukocyte transmigration occurred primarily in the smallest venules and venular convergences (23.9±5.1 and 31.9±2.7 leukocytes/10,000 μm 2 tissue, respectively). In venular convergences, the two inlet vessels are predicted to create a region of low velocity, increasing leukocyte adhesion probability. Conclusions: In straight regions of different‐sized venules, the variability in ICAM‐1 expression accounts for the differences in leukocyte behavior; in converging regions, fluid shear potentially has a greater effect on leukocyte endothelial cell interactions.