Effect of Nicotine on Chorda Tympani Responses to Salty and Sour Stimuli
| Autor: | Vijay Lyall, Tam-Hao T. Phan, Gerd Kobal, John A. DeSimone, Shobha Mummalaneni, Mahdis Mansouri, Gerard L. Heck |
|---|---|
| Rok vydání: | 2007 |
| Předmět: |
Epithelial sodium channel
Nicotine medicine.medical_specialty Taste Physiology Chorda TRPV Cation Channels Sodium Chloride Potassium Chloride chemistry.chemical_compound Transient receptor potential channel Internal medicine Benzamil medicine Animals Epithelial Sodium Channels biology General Neuroscience Hydrogen-Ion Concentration Fluoresceins biology.organism_classification Rats Endocrinology chemistry Chorda Tympani Nerve medicine.drug |
| Zdroj: | Journal of Neurophysiology. 98:1662-1674 |
| ISSN: | 1522-1598 0022-3077 |
| Popis: | The effect of nicotine on the benzamil (Bz)-insensitive (transient receptor potential vanilloid-1 variant cation channel, TRPV1t) and the Bz-sensitive (epithelial Na+ channel, ENaC) salt taste receptors and sour taste was investigated by monitoring intracellular Na+ and H+ activity (pHi) in polarized fungiform taste receptor cells (TRCs) and the chorda tympani (CT) nerve responses to NaCl, KCl, and HCl. CT responses in Sprague–Dawley rats and both wildtype and TRPV1 knockout (KO) mice were recorded in the presence and absence of agonists [resiniferatoxin (RTX) and elevated temperature] and an antagonist (SB-366791) of TRPV1t, the ENaC blocker (Bz), and varying apical pH (pHo). At concentrations 0.015 M, it inhibited CT responses to KCl and NaCl. Nicotine produced maximum enhancement in the Bz-insensitive NaCl CT response at pHo between 6 and 7. RTX and elevated temperature increased the sensitivity of the CT response to nicotine in salt-containing media, and SB-366791 inhibited these effects. TRPV1 KO mice demonstrated no Bz-insensitive CT response to NaCl and no sensitivity to nicotine, RTX, and elevated temperature. We conclude that nicotine modulates salt responses by direct interaction with TRPV1t. At pHo >8, the apical membrane permeability of nicotine was increased significantly, resulting in increase in TRC pHi and volume, activation of ENaC, and enhancement of the Bz-sensitive NaCl CT response. At pHo >8, nicotine also inhibited the phasic component of the HCl CT response. We conclude that the effects of nicotine on ENaC and the phasic HCl CT response arise from increases in TRC pHi and volume. |
| Databáze: | OpenAIRE |
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