Abstracts - Association for Chemoreception Sciences

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any potential role of ryanodine receptors (RyRs) in this signaling pathway has not been identified in mouse taste cells. Using RT- PCR and immunocytochemistry, we detected the RyR isoform 1 in multiple taste papillae types, while calcium imaging studies revealed that RyRs are physiologically functional in mouse taste cells. We found that RyRs significantly contribute to taste-evoked Ca 2+ responses in approximately 30% of type II cells but did not significantly contribute to the taste-evoked responses in dualresponsive taste cells. The discovery of RyRs in mouse taste cells indicates that multiple Ca 2+ release mechanisms contribute to the formation of evoked taste responses and our findings reveal an important role for RyRs in the transduction of these taste-evoked responses. Acknowledgements: This work was supported by NIDCD DC00635801 and NSF 0917893 to KM. #5 PLATFORM PRESENTATIONS - TIP OF THE TONGUE Acetylcholine, released from taste buds during gustatory stimulation, enhances taste responses Robin Dando 1 , Yijen A. Huang 1 , Stephen D. Roper 1,2 1 Department of Physiology and Biophysics, Miller School of Medicine, University of Miami Miami, FL, USA, 2 Program in Neuroscience, Miller School of Medicine, University of Miami Miami, FL, USA Mammalian taste buds possess apical taste receptors as well as basolateral neurotransmitter receptors for synaptic transmission and neuromodulation. One class of basolateral receptors expressed in taste buds are the muscarinic acetylcholine (ACh) receptors (Eguchi et al, 2008), reported to be activated by bathapplied ACh (Ogura, 2002). Acetylcholinesterase has long been known to surround taste buds, suggesting a physiological role for ACh in taste reception. Collectively, these findings implicate a role for ACh in taste bud function. We tested this hypothesis by imaging taste cell responses in lingual slices, and by measuring neurotransmitter secretion from isolated taste buds using cellular biosensors. When we applied ACh or carbachol (1 mM) to a lingual slice, we observed that taste-evoked calcium responses were potentiated. The effects of ACh were blocked by atropine (5 mM), suggesting muscarinic receptor activation. Using ATP biosensors, we measured the effect of bath-applied ACh on ATP secretion from isolated taste buds. ACh augmented taste-evoked ATP release, complementing the ACh potentiation observed in the lingual slice preparation. Moreover, bath-applied atropine itself, in the absence of any added ACh, reduced taste-evoked ATP release from taste buds, suggesting endogenous cholinergic mechanisms are activated during taste stimulation. Finally, we used ACh biosensor cells to test whether taste buds secrete ACh. We observed that ACh is indeed released from isolated taste buds upon tastant stimulation. The source of taste-evoked ACh secretion may be from cholinergic nerve fibers that innervate taste buds or directly from taste cells themselves, as implied by Ogura et al (2007). Our findings strongly implicate ACh as a neurotransmitter that enhances taste responses. Acknowledgements: Supported by NIH/NIDCD grants 5R01DC000374 and 5R01DC007630 to SDR. #6 PLATFORM PRESENTATIONS - TIP OF THE TONGUE Epithelial Sodium Channel (ENaC) is Involved in Reception of Sodium Taste: Evidence from Mice with a Tissue-Specific Conditional Targeted Mutation of the ENaCa Gene Natalia P. Bosak 1 , Masashi Inoue 2 , Theodore M. Nelson 1 , Edith Hummler 3 , Yutaka Ishiwatari 1,4 , Alexander A. Bachmanov 1 1 Monell Chemical Senses Center Philadelphia, PA, USA, 2 Tokyo University of Pharmacy and Life Science Tokyo, Japan, 3 University of Lausanne Lausanne, Switzerland, 4 Institute of Life Sciences, Ajinomoto Co., Inc. Kawasaki, Japan Observations that amiloride and other ENaC blockers alter taste responses to sodium salts generated the hypothesis that ENaC is involved in salt taste reception. To directly test this hypothesis, we have generated mice with the ENaCa subunit selectively eliminated in the lingual epithelium using the Cre-loxP mediated conditional gene deletion technique. Electrophysiological experiments have shown that mice with the tissue-specific conditional ENaCa deletion lacked the amiloride-sensitive component of chorda tympani nerve responses to lingual application of sodium salts. However, the amiloride-insensitive component of the response to sodium salts, responses to nonsodium salts, sweet, bitter and sour taste stimuli, or responses to irritants were not affected in these mice. In brief-access tests, ENaCa knockout mice had an attenuated aversion to higher concentrations of NaCl compared with wild-type mice. These data provide direct evidence that ENaC is involved in detecting sodium taste. Our results further demonstrate that there is a significant ENaC-independent component of taste responses to salts. #7 PLATFORM PRESENTATIONS - TIP OF THE TONGUE Novel proteolyzed ENaC isoforms and corresponding salt taste enhancing compounds Kambiz Shekdar, Jessica Langer, Purvi Shah, Joseph Gunnet, Dennis Sawchuk Chromocell Corporation North Brunswick, NJ, USA Modulators of novel proteolyzed human ENaC isoforms were identified and confirmed in sensory testing to either potentiate or block human salt taste perception. First, a stable ENaC cell line was produced using Chromovert®, a method that enables testing of millions of individual cells to rapidly identify and isolate individual clones stably expressing all desired native subunits. Next, a functional 384-well assay specific for the activity of ENaC comprising alpha, beta and gamma subunits was produced. The cell line was treated with limiting proteolysis in conjunction with the functional assay and a series of novel proteolytic ENaC isoforms was defined based on the differing pharmacology of reference compounds. Interestingly, ENaC isoforms that were less sensitive to inhibition by amiloride were identified, providing a cell based platform consistent with both amiloride-sensitive and amiloride-insensitive components of human salt taste perception. High throughput screening of proteolyzed and non-proteolyzed isoforms resulted in at least 12 distinct chemical series with varied activity against the ENaC isoforms. The creation of and access to multiple distinct ENaC isoforms allowed discovery of corresponding compounds for use as research tools to determine which isoforms correlate with in vivo ENaC activity. Medicinal chemistry and testing of compounds in Ussing chamber models 8 | AChemS Abstracts 2010 Abstracts are printed as submitted by the author(s)
and against delta ENaC is being pursued to further improve nanomolar active compounds for desired safety and efficacy in taste and ENaC-mediated clinical indications including chronic obstructive pulmonary disease (COPD), Cystic Fibrosis and pulmonary edema. Creation of assays for previously inaccessible native and untagged targets comprising all required subunits can aid research in a broad range of applications. Acknowledgements: None #8 PLATFORM PRESENTATIONS - TIP OF THE TONGUE Recovery from Potassium Chloride (KCl) Loading Alters Amiloride-Sensitive Salt Taste in Humans George M Feldman 1,2 , Gerard L Heck 2 , Nancy L Smith 1 1 Dept of Veterans Affairs Richmond, VA, USA, 2 Virginia Commonwealth University Richmond, VA, USA An amiloride sensitive pathway is important for humans to describe NaCl as “salty” after adaptation to NaCl. Since amiloride blocks Na transit through the epithelial sodium channel (ENaC) and ENaC activity in most tissues is regulated by aldosterone, we had hypothesized aldosterone stimulates ENaC activity in the human tongue. However, as we reported previously, when aldosterone production was stimulated by diuretic induced volume depletion, amiloride sensitive salt taste was blunted rather than stimulated. We now report on the effect of aldosterone stimulation induced by KCl loading. KCl loading consisted of ingesting 100 mEq in the evening and again the following morning. 19 subjects participated in 3 days of tests, providing blood samples and magnitude estimates of the component taste qualities (salty, sweet, sour and bitter) of 125 mM NaCl after adaptation to 100 mM NaCl. Day 1 testing occurred prior to KCl loading, Day 2 testing occurred after KCl loading, and Day 3 (recovery) testing was performed two days later. KCl loading increased serum potassium concentration from 4.18 ± 0.06 mEq/L to 4.93 ± 0.09 (p
Page 1: AChemS Association for Chemorecepti
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excite menthol- and/or CA-sensitive
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gene, HMBS was used. All primers we
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oom, without time keeping devices,
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#P113 POSTER SESSION III: OLFACTORY
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decreasing of endogenous volatiles
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may serve to integrate central and
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esponse magnitudes. Inhibitions rea
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the second a non-specific cation ch
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saline. Some of the labeled ORNs sh
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#P166 POSTER SESSION IV: CHEMOSENSO
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pregnancy block. In order to unders
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of GSP neurons and 97% of PA neuron
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concentrations than flies raised on
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#P210 POSTER SESSION V: CENTRAL OLF
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familiarity and cultural difference
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#P265 is found on page 128. #P266 P
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perception of purine 5’-ribonucle
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#P278 POSTER SESSION VI: PERIPHERAL
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(CT), the greater superficial petro
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were significantly different from o
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MSG on NaCl is evidently highlighte
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consisting of motors and IFT comple
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wing. Philip Callahan exposed insec
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seem to indicate that total nasal v
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possibly suggesting non-apoptotic m
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#P325 POSTER SESSION VII: OLFACTORY
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of 7/10, and causing eyes to water
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showed that N1/P2 latencies were lo
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differentiated patients with AD (M=
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pleasantness 3)of mixtures (A,B), A
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Index Aarts, H - P328 Abe, K - P88,
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Haase, L - P3, P4, P29, P355 Haddad
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Murata, Y - P272 Murphy, C - P3, P4
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Veldhuizen, M - P7, P24, P25, P242,
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Registration 7:30 am to 1:00 pm, 6:
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See you next year! AChemS 33rd Annu
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Abstracts - Association for Chemoreception Sciences

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