Passive mechanical behavior of human neutrophils: effect of cytochalasin B

Actin is a ubiquitous protein in eukaryotic cells. It plays a major role in cell motility and in the maintenance and control of cell shape. In this article, we intend to address the contribution of actin to the passive mechanical properties of human neutrophils. As a framework for assessing this con...

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Bibliographic Details
Published in:Biophysical journal 1994-06, Vol.66 (6), p.2166-2172
Main Authors: Tsai, M.A., Frank, R.S., Waugh, R.E.
Format: Article
Language:English
Subjects:
Actins - blood
Actins - physiology
Adult
Cytochalasin B - pharmacology
Cytoplasm - drug effects
Cytoplasm - physiology
Humans
In Vitro Techniques
Kinetics
Neutrophils - drug effects
Neutrophils - physiology
Stress, Mechanical
Time Factors
Viscosity
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Summary:Actin is a ubiquitous protein in eukaryotic cells. It plays a major role in cell motility and in the maintenance and control of cell shape. In this article, we intend to address the contribution of actin to the passive mechanical properties of human neutrophils. As a framework for assessing this contribution, the neutrophil is modeled as a simple viscous fluid drop with a constant cortical ("surface") tension. The reagent cytochalasin B (CTB) was used to disrupt the F-actin structure, and the neutrophil cortical tension and cytoplasmic viscosity were evaluated by single-cell micropipette aspiration. The cortical tension was calculated by simple force balance, and the viscosity was calculated according to a numerical analysis of the cell entry into the micropipette. CTB reduced the cell cortical tension in a dose-dependent fashion: by 19% at a concentration of 3 microM and by 49% at 30 microM. CTB also reduced the cytoplasmic viscosity by approximately -25% at a concentration of 3 microM and by approximately 65% at a concentration of 30 microM when compared at the same aspiration pressures. All three groups of neutrophils, normal cells, and cells treated with either 3 or 30 microM CTB, exhibited non-Newtonian behavior, in that the apparent viscosity decreased with increasing shear rate. The dependence of the cytoplasmic viscosity on deformation rate can be described empirically by mu = mu c(gamma m/gamma c)-b, where mu is cytoplasmic viscosity, gamma m is mean shear rate, mu c is the characteristic viscosity at the characteristic shear rate gamma c, and b is a material coefficient.
ISSN:0006-3495
1542-0086
DOI:10.1016/S0006-3495(94)81012-4