Induction of nitric oxide and prostaglandin e2 in osteoblasts by
wall-shear stress, but not mechanical strain.
Smalt, R, Ft Mitchell, Rl Howard, and Tj Chambers.
Department of Histopathology, St Georges Hospital Medical School,
London SW17 ORE, UK, and Department of Medical Physics, Atkinson
Morleys Hospital, London SW20, UK
APStracts 4:0147E, 1997.
The nature of the stimulus sensed by bone cells during mechanical
usage has not yet been determined. Because nitric oxide (NO) and
prostaglandin (PG) production appear to be essential early responses
to mechanical stimulation in vivo, we used their production to
compare the responsiveness of bone cells to strain and fluid flow in
vitro. Cells were incubated on polystyrene film and subjected to
unidirectional linear strains in the range 500-5000 microstrain (e).
We found no increase in NO or PGE2 production after loading of rat
calvarial or long bone cells, MC3T3-E1, UMR 106.01 or ROS 17/2.8
cells. In contrast, exposure of osteoblastic cells to increased fluid
flow induced both PGE2 and NO production. Production was rapidly
induced by wall-shear stresses of 148 dynes/cm2, and was observed in
all the osteoblastic populations used, but not in rat skin
fibroblasts. Fluid flow appeared to act through an increase in wall
-shear stress. This data suggests that mechanical loading of bone is
sensed by osteoblastic cells through fluid flow-mediated wall-shear
stress, rather than by mechanical strain.
Received 9 January 1997; accepted in final form 7 July 1997.
APS Manuscript Number E0012-7.
Article publication pending Am. J. Physiol. (Endocrinol. Metab.).
ISSN 1080-4757 Copyright 1997 The American Physiological Society.
Published in APStracts on 24 July 1997