title: The deformation of spherical vesicles with permeable, constant-area membranes: application to the red blood cell.
abstract: The deformation of an initially spherical vesicle of radius a with a permeable membrane under extensive forces applied at its poles is calculated as a function of the in-plane shear modulus, H, and the out-of-plane bending modulus, B, using an axisymmetric theory that is valid for large deformations. Suitably nondimensionalized, the results depend upon a single nondimensional parameter, C identical with a(2)H/B. For small deformations, the calculated force-polar strain curves are linear and, under these conditions, the slope of the curve determines only C, not the values of H and B separately. Independent determination of H and B from experimental measurements require deformations that are large enough to produce nonlinear behavior. Simple approximations for large and small C are given, which are applied to experimental measurements on red blood cell ghosts that have been made permeable by treatment with saponin.
authors.affiliation: Physiological Flow Studies Group, Department of Biological and Medical Systems, Imperial College of Science, Technology and Medicine, London SW7 2BY, U.K. k.parker@ic.ac.uk
authors.forename: K H
authors.initials: KH
authors.lastname: Parker
authors.forename: C P
authors.initials: CP
authors.lastname: Winlove
mesh_terms: D001696:Biomechanical Phenomena; D055592:Biophysical Phenomena; D001703:Biophysics; D048429:Cell Size / Q000502:physiology; D004907:Erythrocyte Deformability / Q000502:physiology*; D004910:Erythrocyte Membrane / Q000737:chemistry* / Q000502:physiology; D006801:Humans; D066298:In Vitro Techniques; D008954:Models, Biological; D013314:Stress, Mechanical