Cloning, tissue distribution and functional characterization of the chicken P2X₁ receptor

We describe a new chicken P2X subunit that is an orthologue of the mammalian P2X₁ receptor. Functional characterization of chicken P2X₁ receptors was performed using the amphotericin B perforated patch configuration to avoid the current run-down observed under whole-cell patch-clamp conditions. Responses to agonists and to the antagonist PPADS (pyridoxal 5-phosphate 6-azophenyl-2′,4′-disulfonic acid) were similar to what has been described for mammalian orthologues. However, the antagonists suramin and NF023 were much less potent at chicken P2X₁ receptors than at human P2X₁ receptors. In embryonic tissues, transcript expression is predominant in lung, liver and skeletal muscle. Overlapping expression with cP2X₄ and cP2X₅ subunits in several embryonic tissues, including skeletal muscle, indicates that the native embryonic P2X receptors could be heteromultimeric.