Rotational stiffness of ciliary bundles in cochlea

Range ~2e-14 N×m/rad
Organism Turtle Trachemys scripta elegans
Reference Crawford AC, Fettiplace R. The mechanical properties of ciliary bundles of turtle cochlear hair cells. J Physiol. 1985 Jul364: 359-79. p.359 heading '4' & p.365 bottom paragraphPubMed ID4032304
Method "The object of the work to be described is a quantitative analysis of the mechanical properties of the hair bundles. The approach has been to measure the bending of a single bundle in the turtle cochlea by attaching it to a flexible glass fibre, and monitoring the fibre's motion through its shadowing of a light beam falling on a photodiode array."
Comments "When the fibre was placed at different positions up the bundle, the stiffness decreased approximately as the inverse square of the distance from the ciliary base. This suggests that the bundles rotate about an axis close to the apical pole of the cell and have a rotational stiffness of about 2x10^-14Nxm/rad...The continuous curve in Fig. 4, which is a reasonable fit to the points was calculated from eqn. (4)[K(h)=KR/h^2] with a value of KR of 1.9x10^-14 N×m/rad. When plotted on double logarithmic coordinates, each set of measurements could be fitted with a straight line, the slope of which ranged from 1.3 to 2.1 (mean=1.7). A relationship in which the compliance increases with the square of the height of the fibre up the bundle thus seems the most appropriate to describe the results."
Entered by Uri M
ID 111034