Time-dependent recovery of passive neutrophils after large deformation.
Experiments are performed in which a passive human neutrophil is deformed into an elongated "sausage" shape by aspirating it into a small glass pipette. When expelled from the pipette the neutrophil recovers its natural spherical shape in approximately 1 minute. This recovery process is analyzed according to a Newtonian, liquid-drop model in which a variational method is used to simultaneously solve the hydrodynamic equations for low Reynolds-number flow and the equations for membrane equilibrium with a constant membrane tension. The theoretical model gives a good fit to the experimental data for a ratio of membrane cortical tension to cytoplasmic viscosity of approximately 1.7 x 10(-5) cm/s (0.17 micron/s). However, when the cell is held in the pipette for only a short time period of 5 s or less, and then expelled, the cell undergoes an initial, rapid elastic rebound suggesting that the cell behaves in this instance as a Maxwell viscoelastic liquid rather than a Newtonian liquid with constant cortical tension.
Tran-Son-Tay
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Department of Mechanical Engineering and Materials Science, Duke University, Durham, North Carolina 27706.
Needham
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Yeung
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Hochmuth
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RM
D004548:Elasticity; D006801:Humans; D066298:In Vitro Techniques; D007700:Kinetics; D008433:Mathematics; D008954:Models, Biological; D009504:Neutrophils / Q000502:physiology*; D013500:Surface Tension; D013997:Time Factors; D014783:Viscosity