PHYSIOLOGY OF ISOLATED HUMAN TASTE RECEPTOR CELLS

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Little is known of the transduction mechanisms used by human taste cells. It is the purpose of this application to enhance techniques for taste cell isolation from fungiform papillae of human volunteers and to then investigate the physiological characteristics of these cells. Successful completion of this feasibility study will open new important routes for studying normal human taste response and give impetus to determining the course of human chemosensory disease. The three aims of this study are: to develop protocols to maximize viability of isolated human taste cells; to characterize stimulus-regulated changes in intracellular calcium ion activities and membrane potential in these cells; and to perform loose patch analyses on these cells to identify stimulus-regulated currents in these isolated cells. Procedures developed to date by the investigators on this proposal for isolated human taste cells have yet to be optimized, resulting in unacceptable variations among preparations. In order to allow characterization studies to proceed efficiently, isolation protocols need to be better defined. Experimentation with enzyme type/amount, trituration, media and holding conditions will be performed. Imaging studies of intracellular calcium and membrane potential using the dyes Fura 2 & di-8-ANEPPS will permit basic characterization studies to be performed. These will emphasize characterization of ion channels and normal responses of taste cells to pharmacological challenges. Responses to primarily sweet and bitter stimuli will be evaluated. Loose patch studies will be used to characterize individual cells as to taste modality and chemical specificity. Human taste cells have not been the subject of study for physiological experiments. The unique specificities of human taste can be used to test individual cells. Volunteers can be taste tested prior to have fungiform papillae removed to determine their response to particular stimuli. This research is of high impact since it deals directly with the receptor cells of humans, thereby strengthening the likelihood that therapy regimens can be developed to treat chemosensory disorders. Successful completion of this study will allow correlations to be made between psychophysical measures of taste and biophysical characteristics of the receptor cells. A more complete understanding of peripheral versus central processes of taste will be a likely outcome.