Taste receptor cell responses to the bitter stimulus denatonium involve Ca2+ influx via store-operated channels.
Previous studies in rat and mouse have shown that brief exposure to the bitter stimulus denatonium induces an increase in [Ca2+]i due to Ca2+ release from intracellular Ca2+ stores, rather than Ca2+ influx. We report here that prolonged exposure to denatonium induces sustained increases in [Ca2+]i that are dependent on Ca2+ influx. Similar results were obtained from taste cells of the mudpuppy, Necturus maculosus, as well as green fluorescent protein (GFP) tagged gustducin-expressing taste cells of transgenic mice. In a subset of mudpuppy taste cells, prolonged exposure to denatonium induced oscillatory Ca2+ responses. Depletion of Ca2+ stores by thapsigargin also induced Ca2+ influx, suggesting that Ca2+ store-operated channels (SOCs) are present in both mudpuppy taste cells and gustducin-expressing taste cells of mouse. Further, treatment with thapsigargin prevented subsequent responses to denatonium, suggesting that the SOCs were the source of the Ca2+ influx. These data suggest that SOCs may contribute to bitter taste transduction and to regulation of Ca2+ homeostasis in taste cells.
Ogura
Tatsuya
T
Department of Anatomy and Neurobiology, Colorado State University, Fort Collins, Colorado 80523, USA. Tatsuya.Ogura@colostate.edu
Margolskee
Robert F
RF
Kinnamon
Sue C
SC
D000818:Animals; D002118:Calcium / Q000378:metabolism* / Q000494:pharmacology; D015220:Calcium Channels / Q000502:physiology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D015870:Gene Expression / Q000502:physiology; D051379:Mice; D008822:Mice, Transgenic; D009337:Necturus; D000644:Quaternary Ammonium Compounds; D013268:Stimulation, Chemical; D013649:Taste / Q000502:physiology*; D013650:Taste Buds / Q000502:physiology*; D019284:Thapsigargin / Q000494:pharmacology; D015293:Transducin / Q000235:genetics
D002118:Calcium; D015220:Calcium Channels; D004791:Enzyme Inhibitors; D000644:Quaternary Ammonium Compounds; D019284:Thapsigargin; D015293:Transducin; C043414:denatonium; C075192:gustducin