title: Tank treading of optically trapped red blood cells in shear flow.
abstract: Tank-treading (TT) motion is established in optically trapped, live red blood cells (RBCs) held in shear flow and is systematically investigated under varying shear rates, temperature (affecting membrane viscosity), osmolarity (resulting in changes in RBC shape and cytoplasmic viscosity), and viscosity of the suspending medium. TT frequency is measured as a function of membrane and cytoplasmic viscosity, the former being four times more effective in altering TT frequency. TT frequency increases as membrane viscosity decreases, by as much as 10% over temperature changes of only 4°C at a shear rate of ∼43 s(-1). A threshold shear rate (1.5 ± 0.3 s(-1)) is observed below which the TT frequency drops to zero. TT motion is also observed in shape-engineered (spherical) RBCs and those with cholesterol-depleted membranes. The TT threshold is less evident in both cases but the TT frequency increases in the latter cells. Our findings indicate that TT motion is pervasive even in folded and deformed erythrocytes, conditions that occur when such erythrocytes flow through narrow capillaries.
authors.affiliation: Tata Institute of Fundamental Research, Mumbai, India.
authors.forename: Himanish
authors.initials: H
authors.lastname: Basu
authors.forename: Aditya K
authors.initials: AK
authors.lastname: Dharmadhikari
authors.forename: Jayashree A
authors.initials: JA
authors.lastname: Dharmadhikari
authors.forename: Shobhona
authors.initials: S
authors.lastname: Sharma
authors.forename: Deepak
authors.initials: D
authors.lastname: Mathur
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D002465:Cell Movement; D002470:Cell Survival; D002784:Cholesterol / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D004910:Erythrocyte Membrane / Q000378:metabolism; D004912:Erythrocytes / Q000166:cytology* / Q000378:metabolism; D005456:Fluorescent Dyes / Q000737:chemistry / Q000378:metabolism; D006801:Humans; D055595:Mechanical Phenomena; D051379:Mice; D008863:Microspheres; D057054:Molecular Imaging; D052898:Optical Tweezers; D013696:Temperature; D014783:Viscosity
chemical_list: D005456:Fluorescent Dyes; D002784:Cholesterol