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 contain ing a capillary, which simulates what a cell experiences in a stirred bioreactor. Sf-9 insect cells exhibit an increase in intracellular cal cium concentration, [Ca2+]i when exposed to these cyclic fluid forces. Flow through the capillary spans both the laminar and turbulent regim e and the calcium response is not dependent on the transition to turbu lence. 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 itse lf, indicating that the calcium response is a cellular response to flu id forces and not a matter of increased plasma membrane permeability t o Ca2+ ions. Flow cytometry on hydrodynamically stimulated and unstimu lated cells reveals that the increase in the intracellular calcium con centration averaged over the cell population is due to an increase in intracellular calcium concentration in only a small sub-population of the entire suspension.