Referenced in: none

Automatically associated channels: Kv2.1

Title: Afferent neurotransmission mediated by hemichannels in mammalian taste cells.

Authors: Roman A Romanov, Olga A Rogachevskaja, Marina F Bystrova, Peihua Jiang, Robert F Margolskee, Stanislav S Kolesnikov

Journal, date & volume: EMBO J., 2007 Feb 7 , 26, 657-67

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/17235286

Abstract
In mammalian taste buds, ionotropic P2X receptors operate in gustatory nerve endings to mediate afferent inputs. Thus, ATP secretion represents a key aspect of taste transduction. Here, we characterized individual vallate taste cells electrophysiologically and assayed their secretion of ATP with a biosensor. Among electrophysiologically distinguishable taste cells, a population was found that released ATP in a manner that was Ca(2+) independent but voltage-dependent. Data from physiological and pharmacological experiments suggested that ATP was released from taste cells via specific channels, likely to be connexin or pannexin hemichannels. A small fraction of ATP-secreting taste cells responded to bitter compounds, indicating that they express taste receptors, their G-protein-coupled and downstream transduction elements. Single cell RT-PCR revealed that ATP-secreting taste cells expressed gustducin, TRPM5, PLCbeta2, multiple connexins and pannexin 1. Altogether, our data indicate that tastant-responsive taste cells release the neurotransmitter ATP via a non-exocytotic mechanism dependent upon the generation of an action potential.