FIG. 7.

Act induced release of intracellular stored calcium in human intestinal epithelial cells (HT-29). HT-29 cells labeled with FURA 2-AM were treated with 2.3 μg of Act/ml, and calcium release was measured by fluorescence spectroscopy. Biphasic calcium release from intracellular stores was noted in calcium-free medium. Three independent experiments were performed, and results from a typical experiment are shown. At the end of the experiment 1 μM ionomycin and 67 μM EGTA were added, for measuring, respectively, maximum and minimum calcium release from cells. Arrows indicate the times at which Act, ionomycin, or EGTA were added to the cells.