title: Biophysical implications of lipid bilayer rheometry for mechanosensitive channels.
abstract: The lipid bilayer plays a crucial role in gating of mechanosensitive (MS) channels. Hence it is imperative to elucidate the rheological properties of lipid membranes. Herein we introduce a framework to characterize the mechanical properties of lipid bilayers by combining micropipette aspiration (MA) with theoretical modeling. Our results reveal that excised liposome patch fluorometry is superior to traditional cell-attached MA for measuring the intrinsic mechanical properties of lipid bilayers. The computational results also indicate that unlike the uniform bilayer tension estimated by Laplace's law, bilayer tension is not uniform across the membrane patch area. Instead, the highest tension is seen at the apex of the patch and the lowest tension is encountered near the pipette wall. More importantly, there is only a negligible difference between the stress profiles of the outer and inner monolayers in the cell-attached configuration, whereas a substantial difference (∼30%) is observed in the excised configuration. Our results have far-reaching consequences for the biophysical studies of MS channels and ion channels in general, using the patch-clamp technique, and begin to unravel the difference in activity seen between MS channels in different experimental paradigms.
authors.affiliation: St. Vincent's Clinical School, Faculty of Medicine, University of New South Wales, Darlinghurst, NSW 2010, Australia; Molecular Cardiology and Biophysics Division, Victor Chang Cardiac Research Institute, Darlinghurst, NSW 2010, Australia;
authors.forename: Navid
authors.initials: N
authors.lastname: Bavi
authors.affiliation: Molecular Cardiology and Biophysics Division, Victor Chang Cardiac Research Institute, Darlinghurst, NSW 2010, Australia;
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Nakayama
authors.affiliation: Institute for Nanoscience and Nanotechnology, Sharif University of Technology, 8969414588 Tehran, Iran; and.
authors.forename: Omid
authors.initials: O
authors.lastname: Bavi
authors.affiliation: Molecular Cardiology and Biophysics Division, Victor Chang Cardiac Research Institute, Darlinghurst, NSW 2010, Australia;
authors.forename: Charles D
authors.initials: CD
authors.lastname: Cox
authors.affiliation: Research School of Engineering, Australian National University, Canberra, ACT 0200, Australia.
authors.forename: Qing-Hua
authors.initials: QH
authors.lastname: Qin
authors.affiliation: St. Vincent's Clinical School, Faculty of Medicine, University of New South Wales, Darlinghurst, NSW 2010, Australia; Molecular Cardiology and Biophysics Division, Victor Chang Cardiac Research Institute, Darlinghurst, NSW 2010, Australia; b.martinac@victorchang.edu.au.
authors.forename: Boris
authors.initials: B
authors.lastname: Martinac
mesh_terms: D008051:Lipid Bilayers / Q000737:chemistry*; D008567:Membranes, Artificial; D008956:Models, Chemical; D012212:Rheology / Q000379:methods
chemical_list: D008051:Lipid Bilayers; D008567:Membranes, Artificial
keywords: MscL; azolectin; electrophysiology; finite element modeling