Ct. Hung et al., INTRACELLULAR CA2-TIME CA2+ RESPONSE OF BONE-CELLS EXPERIENCING FLUID-FLOW( STORES AND EXTRACELLULAR CA2+ ARE REQUIRED IN THE REAL), Journal of biomechanics, 29(11), 1996, pp. 1411-1417
In this study, we sought to determine if there is a requirement for ca
lcium entry from the extracellular space as well as calcium from intra
cellular stores to produce real-time intracellular calcium responses i
n cultured bone cells subjected to fluid flow. Understanding calcium c
ell signaling may help to elucidate the biophysical transduction mecha
nism(s) mediating the conversion of fluid dow to a cellular signal. An
experimental design which utilized a scheme of pharmacological blocke
rs was employed to distinguish between the biochemical pathways involv
ed in this cell signaling. A parallel-plate dow chamber served as the
cell stimulating apparatus and a fluorescence microscopy system using
the calcium-sensitive dye fura-2 measured the intracellular calcium ch
anges. In the present study, evidence for a role by the inositol-phosp
holipid biochemical pathway, specifically inositol trisphosphate (IP3)
was obtained using neomycin which completely inhibited the calcium re
sponse to flow. Additionally, a concomitant role of extracellular calc
ium was demonstrated through experiments performed in calcium-free med
ium which also eliminated the dow response. Experiments conducted with
gadolinium, a stretch-activated channel blocker, partially Inhibited
(similar to 30%) the dow response while verapamil, a type-L voltage se
nsitive channel blocker, had no effect on the flow response. These res
ults suggest a requirement of extracellular calcium (or calcium influx
) as well as IP3-induced calcium release from intracellular stores for
generating the intracellular calcium response to flow in bone cells.
Copyright (C) 1996 Elsevier Science Ltd.