Capsaicin binds to the intracellular domain of the capsaicin-activated ion channel

Jooyoung Jung, Sun Wook Hwang, Jiyeon Kwak, Soon Youl Lee, Chang Joong Kang, Won Bae Kim, Donghee Kim, Uhtaek Oh

Research output: Contribution to journalArticle

242 Citations (Scopus)

Abstract

Capsaicin (CAP) excites small sensory neurons, causing pain, neurogenic inflammation, and other visceral reflexes. These effects have been proposed to be the result of CAP activation of a nonselective cation current. It is generally assumed that CAP binds to an extracellular domain of the membrane receptor. However, the exact binding site is not known because of the lipophilic nature of CAR to determine whether the binding domain is extracellular or intracellular, we tested the effect of a synthetic water- soluble CAP analog, DA-5018 · HCl, on current activation. CAP activated the 45 pS (at -60 mV) nonselective cation channel from either side of the membrane. However, DA-5018 · HCl, which had a greater potency and efficacy than CAP, activated the channels only from the cytosolic side of the patch membrane in a capsazepine, a CAP receptor antagonist, reversible manner. When applied extracellularly, DA-5018 · HCl did not, but CAP did, activate whole- cell currents in sensory neurons, as well as in oocytes expressing vanilloid receptor 1, a recently cloned CAP receptor. Hydrogen ions, reported as a possible endogenous activator of cation current, failed to elicit any current when acidic medium (pH 5.0-6.0) was applied intracellularly, indicating that H+ does not mediate the CAP effect. These results indicate that CAP and its analog bind to the cytosolic domain of the CAP receptor and suggest that an endogenous CAP-like substance other than H+ may be present in the cell.

Original languageEnglish
Pages (from-to)529-538
Number of pages10
JournalJournal of Neuroscience
Volume19
Issue number2
Publication statusPublished - 1999 Jan 15
Externally publishedYes

Keywords

  • Acid
  • Binding domain
  • Capsaicin receptor
  • Capsazepine
  • DA-5018
  • Pain
  • VR1

ASJC Scopus subject areas

  • Neuroscience(all)

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    Jung, J., Hwang, S. W., Kwak, J., Lee, S. Y., Kang, C. J., Kim, W. B., Kim, D., & Oh, U. (1999). Capsaicin binds to the intracellular domain of the capsaicin-activated ion channel. Journal of Neuroscience, 19(2), 529-538.