Abstract
Mammals perceive the five different taste qualities: bitter, sweet, umami, sour, and salty. At least two different mechanisms contribute to salt taste in rodents. One is elicited by various cations and sensitive to cetylpyridinium chloride, whereas another is selectively stimulated by Na+ and inhibited by amiloride. The latter pathway has been suggested to involve the epithelial sodium channel, ENaC. In humans, the presence of amiloride-sensitive salt taste transduction is being disputed. In this paper, we addressed the question whether ENaC may have a role in human salt taste perception. Immunohistochemistry revealed that β-, γ-, and δ-ENaC subunits are present in subsets of circumvallate and fungiform taste bud cells, whereas α-ENaC was confined to cells of circumvallate taste buds. Alpha-, β-, and γ-subunits were observed in basolateral intracellular compartments, while δ-ENaC was exclusively found in all taste pores of both types of papillae consistent with a function in taste transduction. To further assess the involvement of ENaC in salt taste transduction, we combined sensory studies and functional expression of ENaC in oocytes. With the exception of l-homoarginine, choline chloride, l-arginine, l-lysine, and l-argininyl-l-arginine enhanced both salt taste perception in subjects and sodium currents recorded in αβγ- or δβγ-ENaC expressing oocytes, whereas l-glutamine did neither show salt-taste-enhancing activity nor did it influence the sodium currents in the oocyte assay. Taken together, our data make ENaC an interesting molecule possibly involved in salty taste transduction.
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Acknowledgments
We thank Ms. Elisabeth Meyer for expert technical assistance and Dr. Erwin Tareilus for the supply of cDNAs encoding α-, β- and γ-ENaC. This work was supported by grants from the Federal Ministry of Education and Research (BMBF) to W.M. (0313819A) and T.H. (0313819B).
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Fig. S1
Immunohistochemistry omitting primary antibodies in circumvallate and fungiform papillae. Indirect immunohistochemistry was performed without primary antibodies using 2-μm sections of paraffin-embedded human circumvallate and fungiform papillae. Detection with peroxidase-conjugated secondary antibody resulted in no labeling at all. Dotted lines mark taste buds within taste papillae (GIF 103 KB).
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Stähler, F., Riedel, K., Demgensky, S. et al. A Role of the Epithelial Sodium Channel in Human Salt Taste Transduction?. Chem. Percept. 1, 78–90 (2008). https://doi.org/10.1007/s12078-008-9006-4
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DOI: https://doi.org/10.1007/s12078-008-9006-4