Biomechanics of hair cell kinocilia: experimental measurement of kinocilium shaft stiffness and base rotational stiffness with Euler-Bernoulli and Timoshenko beam analysis

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dc.contributor.authorSpoon, Corrie E.en
dc.contributor.authorGrant, John Wallaceen
dc.contributor.departmentBiomedical Engineering and Mechanicsen
dc.contributor.departmentSchool of Biomedical Engineering and Sciencesen
dc.date.accessed2014-02-04en
dc.date.accessioned2014-02-07T18:29:41Zen
dc.date.available2014-02-07T18:29:41Zen
dc.date.issued2011-03-01en
dc.description.abstractVestibular hair cell bundles in the inner ear contain a single kinocilium composed of a 9+2 microtubule structure. Kinocilia play a crucial role in transmitting movement of the overlying mass, otoconial membrane or cupula to the mechanotransducing portion of the hair cell bundle. Little is known regarding the mechanical deformation properties of the kinocilium. Using a force-deflection technique, we measured two important mechanical properties of kinocilia in the utricle of a turtle, Trachemys (Pseudemys) scripta elegans. First, we measured the stiffness of kinocilia with different heights. These kinocilia were assumed to be homogenous cylindrical rods and were modeled as both isotropic Euler-Bernoulli beams and transversely isotropic Timoshenko beams. Two mechanical properties of the kinocilia were derived from the beam analysis: flexural rigidity (El) and shear rigidity (kGA). The Timoshenko model produced a better fit to the experimental data, predicting El=10,400 pN mu m(2) and kGA=247 pN. Assuming a homogenous rod, the shear modulus (G=1.9 kPa) was four orders of magnitude less than Young's modulus (E=14.1 MPa), indicating that significant shear deformation occurs within deflected kinocilia. When analyzed as an Euler-Bernoulli beam, which neglects translational shear, El increased linearly with kinocilium height, giving underestimates of El for shorter kinocilia. Second, we measured the rotational stiffness of the kinocilium insertion (kappa) into the hair cell's apical surface. Following BAPTA treatment to break the kinocilial links, the kinocilia remained upright, and kappa was measured as 177 +/- 47 pN mu m rad(-1). The mechanical parameters we quantified are important for understanding how forces arising from head movement are transduced and encoded by hair cells.en
dc.description.sponsorshipNational Institutes of Health NIDCD RO1 DC 05063en
dc.description.sponsorshipInstitutes of Health NIDCD RO1 DC 002290-12en
dc.format.mimetypeapplication/pdfen
dc.identifier.citationSpoon, Corrie; Grant, Wally. "Biomechanics of hair cell kinocilia: experimental measurement of kinocilium shaft stiffness and base rotational stiffness with Euler-Bernoulli and Timoshenko beam analysis," J Exp Biol 214, 862-870 (2011); doi: 10.1242/_jeb.051151en
dc.identifier.doihttps://doi.org/10.1242/jeb.051151en
dc.identifier.issn0022-0949en
dc.identifier.urihttp://hdl.handle.net/10919/25348en
dc.identifier.urlhttp://jeb.biologists.org/content/214/5/862.full.pdf+htmlen
dc.language.isoenen
dc.publisherCompany of Biologistsen
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subjectBase rotational stiffnessen
dc.subjectBeam model analysisen
dc.subjectFlexural rigidityen
dc.subjectKinocilium stiffnessen
dc.subjectEchinoderm sperm flagellaen
dc.subjectFlexural rigidityen
dc.subjectMechanical propertiesen
dc.subjectSingle microtubuleen
dc.subjectElastic propertiesen
dc.subjectBundlesen
dc.subjectHeightsen
dc.subjectLengthen
dc.titleBiomechanics of hair cell kinocilia: experimental measurement of kinocilium shaft stiffness and base rotational stiffness with Euler-Bernoulli and Timoshenko beam analysisen
dc.title.serialJournal of Experimental Biologyen
dc.typeArticleen
dc.type.dcmitypeTexten

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