Taste is a complex process beginning in the tongue, where the surface layer of cells, the epithelium, contains taste buds. Many taste compounds probably bind to specific receptor molecules on membrane of the taste sensory cells. But salts form a whole class of tastants that produce ions in solution, and now are thought to stimulate the cells of the taste buds directly, by transport processes across the cell membrane. These ions may use specific channels in the membrane in a way similar to the use of ionic channels in to stimulate excitable membranes of nerve and muscle. Understanding taste transduction, by which a particular stimulus specifically excites a sensory cell, is a major goal of chemosensory systems research. This project will approach taste transduction by linking experiments on the physiology of tongue epithelial tissue with neurophysiology of taste receptors. In vitro tongue tissue will be tested to precisely measure ionic flows, and a mathematical model of ionic transport processes across the epithelium will be refined and expanded by comparisons to data from experiments. These data will be compared to known data on excitation of taste nerves from neurophysiology experiments. Experiments and modelling should resolve which aspects of taste transduction can be explained by properties of the tongue epithelium. The model incorporates organization of all the component membranes, and the topology of the epithelium in which the taste buds are imbedded; the model can be extended to include different cell types and different ions. This study involves a novel quantitative approach to taste mechanisms, with a powerful merging of mathematics, chemistry, and biology; it may be useful in analyses of tastant interactions by the food industry, and will have high impact in chemosensory science and neurophysiology as well.
