TNP-ATP-resistant P2X ionic current on the central terminals and somata of rat primary sensory neurons

Kenzo Tsuzuki, Ariel Ase, Philippe Séguéla, Terumasa Nakatsuka, Cong Yi Wang, Jin Xiong She, Jianguo G. Gu

Research output: Contribution to journalArticlepeer-review

34 Scopus citations


P2X receptors have been suggested to be expressed on the central terminals of Aδ-afferent fibers innervating dorsal horn lamina V and play a role in modulating sensory synaptic transmission. These P2X receptors have been widely thought to be P2X2+3 receptors. However, we have recently found that P2X receptor-mediated modulation of sensory transmission in lamina V is not inhibited by trinitrophenyl-adenosine triphosphate (TNP-ATP), a potent antagonist of P2X1, P2X3 homomers, and P2X2+3 heteromers. To provide direct evidence for the presence of TNP-ATP-resistant P2X receptors on primary afferent fibers, we examined α,β-methylene-ATP (αβmeATP)-evoked currents and their sensitivity to TNP-ATP in rat dorsal root ganglion (DRG) neurons, αβmeATP evoked fast currents, slow currents, and mixed currents that contained both fast and slow current-components. Fast currents and fast current components in the mixed currents were both completely inhibited by 0.1 μM TNP-ATP (n = 14). Both slow currents and slow-current components in the mixed currents showed broad spectrum of sensitivity to 1 μM TNP-ATP, ranging from complete block (TNP-ATP-sensitive) to little block (TNP-ATP-resistant). TNP-ATP-resistant currents evoked by 10 μM αβmeATP could be largely inhibited by 10 μM iso-pyridox-alphosphate-6-azophenyl-2′,4′-disulphonic acid. Cells with P2X currents that were highly resistant to TNP-ATP were found to be insensitive to capsaicin. These results suggest that TNP-ATP-resistant P2X receptor subtypes are expressed on capsaicin-insensitive Aδ-afferent fibers and play a role in modulating sensory transmission to lamina V neurons.

Original languageEnglish (US)
Pages (from-to)3235-3242
Number of pages8
JournalJournal of Neurophysiology
Issue number6
StatePublished - Jun 1 2003
Externally publishedYes

ASJC Scopus subject areas

  • Neuroscience(all)
  • Physiology


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