Analysis and modeling of the primary cilium bending response to
fluid shear.
Schwartz, Eric A., Michelle L. Leonard, Rena Bizios, and Samuel S.
Bowser.
Department of Biomedical Engineering, Rensselaer Polytechnic
Institute, Troy, NY 12180-3590; Laboratory of Cell Regulation,
Wadsworth Center, New York State Department of Health, Albany, NY
12201-0509; and Department of Biomedical Sciences, The University at
Albany, State University of New York, Albany, NY 12222
APStracts 3:0175F, 1996.
Since a nonmotile, primary (9+0) cilium projects from most mammalian
kidney epithelial cells into the tubule lumen, where it is exposed to
fluid motion, the present study examined primary cilium response to
fluid shear stress. The reversible, large-angle bending of the
primary cilium upon exposure to fluid shear forces (10_11 _ 10_10
Nm2; = 10_8 _ 10_7 dynes/cm) was characterized in vitro using
videomicroscopic side-views of PtK1 cells, and the cilium was then
mathematically modeled as a cantilevered beam. The flexural rigidity
of the primary cilium was calculated to be 3.1 +/- 0.8 x 10_23 Nm2
using a corrected quadruple integration approach, and 1.4 _ 1.6 x
10_23 Nm2 using Heavy Elastica theory. Comparison of theoretical
profiles to the experimental bending responses of cilia established
the validity of the Heavy Elastica Model; this model, in turn, was
used to predict primary cilium bending behavior under representative
conditions in the rat nephron. The results of the study are
consistent with the hypothesis that primary cilia serve a
mechanosensory function in kidney epithelial cells.
Received 31 October 1995; accepted in final form 19 September
1996.
APS Manuscript Number F373-5.
Article publication pending Am. J. Physiol. (Renal Fluid Electrolyte
Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 5 November 1996