Staphylococcal enterotoxin A modulates intracellular Ca 2+ signal pathway in human intestinal epithelial cells

We demonstrate here that staphylococcal enterotoxin A (SEA) induces an increase in intracellular calcium ([Ca 2+ ] i ) in human intestinal epithelial cells and the [Ca 2+ ] i is released from intracellular stores. SEA‐induced increase of [Ca 2+ ] i was clearly inhibited by treatment with a nitric oxide synthase (NOS) inhibitors, N G ‐monomethyl‐ L ‐arginine and guanidine. Intestinal epithelial cells express endothelial NOS in resting cell condition, and express inducible NOS after stimulating with tumor necrosis factor (TNF)‐α. TNF‐α‐pretreated cells showed a significant increase in [Ca 2+ ] i that was also inhibited by the NOS inhibitor. These results suggest that SEA modulated [Ca 2+ ] i signal is dependent on NOS expression in human intestinal epithelial cells.