Intracellular calcium response of Sf-9 insect cells exposed to intense fluid forces.

Suspension cell cultures are exposed to periodic high intensity, short duration fluid forces by circulating them through a flow loop containing a capillary, which simulates what a cell experiences in a stirred bioreactor. Sf-9 insect cells exhibit an increase in intracellular calcium concentration, [Ca2+]i when exposed to these cyclic fluid forces. Flow through the capillary spans both the laminar and turbulent regime and the calcium response is not dependent on the transition to turbulence. The calcium response is a nearly linear function of the rate of energy dissipation per mass of fluid in the capillary. The source of the increased calcium ions in the cell cytosol is within the cell itself, indicating that the calcium response is a cellular response to fluid forces and not a matter of increased plasma membrane permeability to Ca2+ ions. Flow cytometry on hydrodynamically stimulated and unstimulated cells reveals that the increase in the intracellular calcium concentration averaged over the cell population is due to an increase in intracellular calcium concentration in only a small sub-population of the entire suspension.