Neonatal rat calvarial cells (osteoblast-enriched) were cultured in mo
nolayer on glass slides and subjected to a step increase in shear stre
ss ranging from 3 to 60 dyne/cm(2) in a laminar flow chamber. The leve
l of intracellular free calcium ion concentration was monitored using
Fura-2 fluorescence during the application of stress. Application of a
step increase in stress resulted in a transient increase in calcium s
tarting about 10-20 s after turning on the pump, reaching a peak in ab
out 35 s and declining thereafter, despite the continued shear stress,
and reaching near baseline values in about 100 s. No change in cytopl
asmic calcium was observed with a step increase in shear stress of 3 d
yne/cm(2) Between 6 dyne/cm(2) and 60 dyne/cm(2) the magnitude of the
calcium response increased with the applied shear stress.