Co-Localization of Epithelial Sodium Channels and Glutamate Receptors in Single Taste CellsLin W. · Kinnamon S.C.
aDepartment of Anatomy and Neurobiology, Colorado State University, Fort Collins, Colo., and bRocky Mountain Taste and Smell Center, University of Colorado Health Sciences Center, Denver, Colo., USA
Umami taste is elicited by monosodium glutamate (MSG), a compound consisting of two potent taste stimuli, Na+ and glutamate. In rat fungiform taste cells, amiloride-sensitive epithelial sodium channels (ENaCs) mediate Na+ transduction, while glutamate is transduced by a combination of ionotropic and metabotropic glutamate receptors. We used giga-seal whole-cell recording to determine if responses to glutamate and Na+ occur in the same taste cells. Approximately 68% of the cells tested responded to amiloride, indicating that they express functional ENaCs. Responses to glutamate occurred in about 58% of the cells tested. Interestingly, responses to glutamate occurred in the subset of cells that also responded to amiloride, indicating that glutamate receptors are located preferentially in the same taste cells that also express ENaCs. Further experiments showed that amiloride did not suppress responses to glutamate under voltage-clamp conditions. Taken together, the data suggest that although ENaCs are not involved directly in glutamate transduction, their co-localization with glutamate receptors provides a substrate for the cellular integration of these independent pathways.
Dr. Weihong Lin
Department of Anatomy and Neurobiology
Colorado State University
Fort Collins, CO 80523 (USA)
Tel. +1 970 491 3801, Fax +1 970 491 7907
Number of Print Pages : 6
Number of Figures : 3, Number of Tables : 0, Number of References : 25
Biological Signals and Receptors
Vol. 8, No. 6, Year 1999 (Cover Date: November-December 1999)
Journal Editor: S.F. Pang, Hong Kong; P.A. Ward, Ann Arbor, Mich.; D.P. Cardinali, Buenos Aires
ISSN: 1422–4933 (print), 1422–4992 (Online)
For additional information: http://www.karger.com/journals/bsi