Changes in Outward K+ Currents in Response to Two Types of Sweeteners in Sweet Taste Transduction of Gerbil Taste Cells

• Published in: Chemical senses Vol. 22; no. 2; pp. 163 - 169
• Main Authors: Uchida, Yoshinori, Sato, Toshihide
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Oxford Oxford University Press 01.04.1997
• Subjects: Animals; Biological and medical sciences; Calcium - metabolism; Cyclic AMP - metabolism; Fundamental and applied biological sciences. Psychology; Gerbillinae; Inositol 1,4,5-Trisphosphate - pharmacology; Ion Transport - drug effects; Ionomycin - pharmacology; Ionophores - pharmacology; Membrane Potentials - drug effects; Olfactory system and olfaction. Gustatory system and gustation; Patch-Clamp Techniques; Plant Proteins - pharmacology; Potassium Channels - drug effects; Potassium Channels - metabolism; Saccharin - pharmacology; Signal Transduction - drug effects; Sweetening Agents - pharmacology; Taste - drug effects; Taste - physiology; Taste Buds - cytology; Taste Buds - drug effects; Taste Buds - metabolism; Tryptophan - pharmacology; Vertebrates: nervous system and sense organs; Meriones unguiculatus; Rodentia; Electrophysiology; Patch clamp method; Outward current; Signal transduction; Vertebrata; Mammalia; Gustation; Perception; Sensory neuron; Sweet taste; Sweetener; Potassium; Chemical stimulus
• ISSN: 0379-864X; 1464-3553
• DOI: 10.1093/chemse/22.2.163

Using the whole cell patch clamp technique, we measured changes in outward K+ currents of gerbil taste cells in response to different kinds of sweeteners. Outward K+ currents of the taste cell induced by depolarizing pulses were suppressed by sweet stimuli such as 10 mM Na-saccharin. The membrane-permeable analog of cAMP, cpt-cAMP, also decreased outward K+ currents. On the other hand, the K+ currents were enhanced by amino acid sweeteners such as 10 mM D-tryptophan. The outward K+ current was enhanced by external application of Ca2+-transporting ionophore, 5 μM ionomycin, and intracellular application of 5 μM inositol-1,4,5-trisphosphate (IP3). The outward K+ currents were no longer suppressed by 10 mM Na-saccharin containing 20 μM gurmarin, but were still enhanced by 10 mM D-tryptophan containing 20 μM gurmarin. These results suggest that sweet taste transduction for one group of sweeteners such as Na-saccharin in gerbils is concerned with an increase of the intracellular cAMP level, and that the transduction for the other group of sweeteners such as D-tryptophan is concerned with an increase of the intracellular IP3 level which releases Ca2+ from the internal stores. Chem. Senses 22: 163–169, 1997.