Bitter and sweet receptors (T2Rs and T1Rs) are expressed in many extra-oral tissues including upper and lower airways. To investigate if bitter tastants and artificial sweeteners could activate physiological responses in tracheal epithelial cells we performed confocal Ca2+ imaging recordings on acute tracheal slices. We stimulated the cells with denatonium benzoate, a T2R agonist, and with the artificial sweeteners sucralose, saccharin and acesulfame-K. To test cell viability we measured responses to ATP. We found that 39% of the epithelial cells responding to ATP also responded to bitter stimulation with denatonium benzoate. Moreover, artificial sweeteners activated different percentages of the cells, ranging from 5% for sucralose to 26% for saccharin, and 27% for acesulfame-K. By using carbenoxolone, a gap junction blocker, we excluded that responses were mainly mediated by Ca2+ waves through cell-to-cell junctions. Pharmacological experiments showed that both denatonium and artificial sweeteners induced a PLC-mediated release of Ca2+ from internal stores. In addition, bitter tastants and artificial sweeteners activated a partially overlapping subpopulation of tracheal epithelial cells. Our results provide new evidence that a subset of ATP-responsive tracheal epithelial cells from rat are activated by both bitter tastants and artificial sweeteners.
Bitter tastants and artificial sweeteners activate a subset of epithelial cells in acute tissue slices of the rat trachea / Lasconi, C.; Pifferi, S.; Hernandez-Clavijo, A.; Merigo, F.; Cecchini, M. P.; Gonzalez-Velandia, K. Y.; Agostinelli, E.; Sbarbati, A.; Menini, A.. - In: SCIENTIFIC REPORTS. - ISSN 2045-2322. - ELETTRONICO. - 9:1(2019), p. 8834. [10.1038/s41598-019-45456-w]