Adenosine triphosphate mobilizes cytosolic calcium and modulates ionic currents in mouse taste receptor cells.

By using photometry and the patch clamp technique, we identified P(2Y)-like receptors in mouse taste receptor cells (TRCs) and found them to be coupled to Ca(2+) mobilization and ionic current modulation. Particularly, adenosine triphosphate (ATP) and the P(2Y) agonist 2-methylthio-ATP increased intracellular Ca(2+) by stimulating the phosphoinositide pathway, whereas beta, gamma-methylene-D-ATP, a P(2X) agonist, was ineffective. In a distinctive TRC subpopulation, ATP closed Ca(2+) channels. This regulation may underlie the negative feedback tuning neurotransmitter release. By mobilizing intracellular Ca(2+), ATP activated Ca(2+)-dependent Cl(-) channels, the intracellular event that may universally occur upon taste stimulation triggering IP(3) formation and Ca(2+) release in the TRC cytoplasm.