title: Leukocyte rolling velocity and its relation to leukocyte-endothelium adhesion and cell deformability.
abstract: To explore the relationship between the rolling velocity of leukocytes (VWBC) and wall shear rates (gamma), measurements of VWBC were made along the length of rat mesenteric venules in which a gradient in gamma was induced by compressing the venule with a blunted microprobe to form a stenosis in which gamma varied from 300 to 1500 s-1. For individual WBCs that rolled through stenosis, VWBC was proportional to gamma for its entire range, in contrast to previous studies that have shown a plateau in VWBC vs. gamma for the ensemble population. Comparisons of the slope of VWBC/gamma for individual cells with ensemble values of VWBC obtained in the entrance region of the stenosis were made during suffusion of the tissue with the chemoattractant N-formylmethionyl-leucyl-phenylalanine (FMLP), to increase WBC-EC adhesion and WBC stiffness, or colchicine and cytochalasin B to increase WNC deformability. Under control conditions, the slope of individual cells was significantly 20% greater than VWBC/gamma, whereas it was significantly reduced by 48% during suffusion with FMLP. With exposure to colchicine, the slope was 78% lower than VWBC/gamma and compared with control was similar in magnitude to that obtained with FMLP. Cytochalasin also reduced the slope by 22% compared with control and 34% compared with VWBC/ gamma. The diminished slopes of VWBC vs. gamma were consistent with published theoretical models that suggest a reduced slope with increased strength of adhesion of WBC deformability. It is thus concluded that the apparent plateau in VWBC vs. gamma arises due to the heterogeneity of adhesive and/or deformability properties in the ensemble population of circulating WBCs.
authors.affiliation: Bioengineering Program, Pennsylvania State University, University Park 16802, USA. hhlbio@enger.psu.edu
authors.forename: H H
authors.initials: HH
authors.lastname: Lipowsky
authors.forename: D A
authors.initials: DA
authors.lastname: Scott
authors.forename: J S
authors.initials: JS
authors.lastname: Cartmell
mesh_terms: D000818:Animals; D002448:Cell Adhesion / Q000187:drug effects; D003078:Colchicine / Q000494:pharmacology; D003571:Cytochalasin B / Q000494:pharmacology; D004730:Endothelium, Vascular / Q000502:physiology*; D005260:Female; D007962:Leukocytes / Q000187:drug effects / Q000502:physiology*; D008297:Male; D008955:Models, Cardiovascular; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D013314:Stress, Mechanical
chemical_list: D003571:Cytochalasin B; D009240:N-Formylmethionine Leucyl-Phenylalanine; D003078:Colchicine