MECHANISMS OF SWEET TASTE TRANSDUCTION

Models of saccharide-stimulated responses in taste cells are presented based on electrophysiological, pharmacological and morphological investigations. Two models are most consistent with the available data. In both these models, saccharides bind to receptors on the apical membrane of taste cells causing them to depolarize. This depolarization results in the generation of action potentials in nerves synapsed to them. In the first model, the binding of saccharides to receptors opens an amiloride-inhibitable channel permitting small cations to enter and depolarize taste cells. Such a model is consistent with salt-modulating saccharide responses. In the second model the binding of saccharides to receptors activates a second messenger cascade that either closes potassium channels and/or opens chloride channels. In the second model, taste transduction can occur in the absence of salts.