Taste transduction starts off the recognition of tastants by specialized receptors in the apical membrane of taste cells and ends with the encoding of sensory information in the form of a stimulus-dependent release of the afferent neurotransmitter ATP, which stimulates the taste nerve. This process has been studied in detail at the level of type II single cells expressing specialized taste GPCR receptors of the T1 and T2 families. It has been shown that, upon transduction of a taste signal, synaptic transmission is ensured by the functioning of a non-canonical chemical synapse in type II taste cells: ATP is released in a Ca2+ -independent manner through ATP-permeable ion channels of the basolateral membrane. Meanwhile, in single cell experiments it is practically impossible to stimulate only the apical membrane of cells; however, this is feasible when registering the activity of the taste epithelium due to the physical isolation of the apical and basolateral parts. To study the secretion of ATP by taste cells under conditions of physiologically adequate stimulation, we used a modernized Ussing chamber provided an opportunity to stimulate separately the apical part of taste cells exposed to the upper cell of the chamber and to detect ATP secreted from the basal part of the epithelium into the lower cell of the chamber filled with a mixture of luciferin-luciferase. The developed experimental scheme made it possible to on-line register a series of ATP releases by the taste epithelium in response to stimulation of the apical part of the epithelium with bitter taste substances.
Ussing chamber, luciferin-luciferase, ATP secretion, taste epithelium
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