Extracellular ATP induces cytosolic calcium oscillations associated with an increase in intracellular pH in human Chang liver cells.

Phosphoinositide (PI) signal transduction pathways are known to be involved in the modulation of several key cellular functions. In this study, ATP is observed to induce calcium transients which appeared to oscillate depending on the ATP concentration. Since higher doses of ATP are known to be toxic to cells, an increase in amplitude could possibly be an inherent cellular protective mechanism. Mobilization of cytosolic calcium from intracellular stores is mediated by the PI second messenger, inositol 1,4,5 trisphosphate. The raised cytosolic calcium was also associated with a rise in intracellular pH in a concentration dependent manner in ATP-treated cells. Intracellular alkalinization is an important parameter in the control of cellular responses.