To explore the relationship between the rolling velocity of leukocytes (V(WBC)) and wall shear rates (γ̇), measurements of V(WBC) were made along the length of rat mesenteric venules in which a gradient in γ̇ was induced by compressing the venule with a blunted microprobe to form a stenosis in which γ̇ varied from 300 to 1500 s-1. For individual WBCs that rolled through the stenosis, V(WBC) was proportional to γ̇ its entire range, in contrast to previous studies that have shown a plateau in V(WBC) vs. γ̇ for the ensemble population. Comparisons of the slope of V(WBC) vs. γ̇ for individual cells with ensemble values of V(WBC)/γ̇ 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 WBC deformability. Under control conditions, the slope of individual cells was significantly 20% greater than V(WBC)/γ̇, whereas it was significantly reduced by 48% during suffusion with FMLP. With exposure to colchicine, the slope was 78% lower than V(WBC)/γ̇ 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 V(WBC)/γ̇. The diminished slopes of V(WBC) vs. γ̇ were consistent with published theoretical models that suggest a reduced slope with increased strength of adhesion or WBC deformability. It is thus concluded that the apparent plateau in V(WBC) vs γ̇ arises due to the heterogeneity of adhesive and/or deformability properties of the ensemble population of circulating WBCs.
|Original language||English (US)|
|Journal||American Journal of Physiology - Heart and Circulatory Physiology|
|Issue number||4 39-4|
|State||Published - 1996|
All Science Journal Classification (ASJC) codes
- Cardiology and Cardiovascular Medicine
- Physiology (medical)