Umami Changes Intracellular Ca^<2+> Levels Using Intracellular and Extracellular Sources in Mouse Taste Receptor Cells

概要

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Recently, candidates for umami receptors have been identified in taste cells, but the precise transduction mechanisms of the downstream receptor remain unknown. To investigate how intracellular Ca2+ increases in the umami transduction pathway, we measured changes in intracellular Ca2+ levels in response to umami stimuli monosodium glutamate (MSG), IMP, and MSG + IMP in mouse taste receptor cells (TRCs) by Ca2+ imaging. Even when extracellular Ca2+ was absent, 1/3 of umami-responsive TRCs exhibited increased intracellular Ca2+ levels. When intracellular Ca2+ was depleted, half of the TRCs retained their response to umami. These results suggest that umami-responsive TRCs increase their intracellular Ca2+ levels through two pathways: by releasing Ca2+ from intracellular stores and by an influx of Ca2+ from extracellular sources. We conclude that the Ca2+ influx from extracellular source might play an important role in the synergistic effect between MSG and IMP.
社団法人日本農芸化学会の論文
2006-11-23