International Journal of Oral Biology

The Korean Academy of Oral Biology (대한구강생물학회)
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Pharmacological and electrophysiological characterization of rat P2X currents

  • Li, Hai-Ying (Department of Physiology and Program in Molecular and Cellular Neuroscience, School of Dentistry and Dental Research Institute, Seoul National University) ;
  • Oh, Seog-Bae (Department of Physiology and Program in Molecular and Cellular Neuroscience, School of Dentistry and Dental Research Institute, Seoul National University) ;
  • Kim, Joong-Soo (Department of Physiology and Program in Molecular and Cellular Neuroscience, School of Dentistry and Dental Research Institute, Seoul National University)
  • Published : 2008.03.31
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Abstract

Adenosine 5'-triphosphate (ATP) is an important extracellular signaling molecule which is involved in a variety of physiological responses in many different tissues and cell types, by acting at P2 receptors, either ionotropic (P2X) or G protein-coupled metabotropic receptors (P2Y). P2X receptors have seven isoforms designated as $P2X_{1^-}P2X_7$. In this study, we investigated the electrophysiological and pharmacological properties of rat $P2X_{1^-}P2X_4$ currents by using whole-cell patch clamp technique in a heterologous expression system. When ATP-induced currents were analyzed in human embryonic kidney (HEK293) cells following transient transfection of rat $P2X_{1^-}P2X_4$, the currents showed different pharmacological and electrophysiological properties. ATP evoked inward currents with fast activation and fast desensitization in $P2X_{^1-}$ or $P2X_{3^-}$ expressing HEK293 cells, but in $P2X_{2^-}$ or $P2X_{4^-}$ expressing HEK293 cells, ATP evoked inward currents with slow activation and slow desensitization. While PPADS and suramin inhibited $P2X_2$ or $P2X_3$ receptor-mediated currents, they had little effects on $P2X_4$ receptor-mediated currents. Ivermectin potentiated and prolonged $P2X_4$ receptor-mediated currents, but did not affect $P2X_2$ or $P2X_3$ receptor-mediated currents. We suggest that distinct pharmacological and electrophysiological properties among P2X receptor subtypes would be a useful tool to determine expression patterns of P2X receptors in the nervous system including trigeminal sensory neurons and microglia.

Keywords

References

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