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KMID : 0848120080330010001
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International Journal of Oral Biology
2008 Volume.33 No. 1 p.1 ~ p.5
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Pharmacological and electrophysiological characterization of rat P2X currents
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Li Hai-Ying
Oh Seog-Bae
Kim Joong-Soo
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Abstract
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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 P2X1-P2X7. In this study, we investigated the electrophysiological and pharmacological properties of rat P2X1-P2X4 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 P2X1-P2X4 , the currents showed different pharmacological and electrophysiological properties. ATP evoked inward currents with fast activation and fast desensitization in P2X1_ of P2X3- expressing HEK293 cells, but in P2X2- or P2X4- expressing HEK293 cells, ATP evoked inward currents with slow activation and slow desensitization. While PPADS and suramin inhibited P2X2 or P2X3 receptor-mediated currents, they had little effects on P2X4 receptor-mediated currents. Ivermectin potentiated and prolonged P2X4 receptor-mediated currents, but did not affect P2X2 or P2X3 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.
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KEYWORD
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ATP, ivermectin, P2X receptors, PPADS, surarmin
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