The interaction of a tastant with the receptor has long been believed to occur at the surface of the taste cell membrane (Beidler, 1954, 1962; Kennedy & Halpern, 1980). Among the evidence cited by Beidler (1962) for that conclusion is: (1) the threshold concentration of sodium chloride is reached within a millisecond after 01 M sodium chloride has been applied to the tongue; (2) sucrose does not penetrate the membrane of any type of cell that has been investigated, and lead acetate and beryllium chloride, which also taste sweet, are very toxic when they reach the interior of a cell; (3) a taste receptor rapidly elicits a steady electrophysiological response, and the magnitude is proportionate to the stimulus concentration; and (4) the taste response declines rapidly following a water rinse. It also stands to reason (albeit, ideologically) that the taste response is a chemical property index to chemical activity before ingestion. Many investigators subscribe to the Beidler tenet. Others believe ions must pass through the cell membrane to elicit saltiness (cf. Teeter & Cagan, 1989; Lancet & Ben-Arie, 1991; Schiffman, 1990). On the whole, it seems to be generally agreed that the initial chemistry of all tastes occurs at a membrane surface and good account of the probable chemical events responsible for different tastes can be formulated, based on that premise alone.
KeywordsSugar Sodium Chloride Caffeine Alkaloid Galactose
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