Effects of ethanol and zinc ions on 5'- adenosine triphosphate gated P2X3 receptor expressed in Xenopus oocytes

  Objective  To investigate the effects of ethanol and zinc ions (Zn²⁺) on the recombinant P2X3 receptor expressed in Xenopus oocytes.

  Methods  Bipolar voltage clamp technique was used to detect the effects of ethanol and Zn²⁺ on P2X3 receptor mediated 5'- adenosine triphosphate (ATP) gated current expressed in Xenopus oocytes. The experiment was divided into three groups. The first group explored the effects of different concentrations of ethanol on the expression of P2X3 receptor mediated ATP current in Xenopus oocytes, and the ATP concentration-response curve of P2X3 receptor in the presence and absence of ethanol. In the second group, the effects of different concentrations of Zn²⁺ on the expression of P2X3 receptor mediated ATP currents in Xenopus oocytes and the ATP concentration-response curve of P2X3 receptor in the presence and absence of Zn²⁺ were investigated. The third group studied the effect of ethanol and Zn²⁺ on ATP gated P2X3 receptor expressed in Xenopus oocytes.

  Results  Ethanol (5~200 mmol/L) reversibly enhanced the ATP-gated function of P2X3 receptor expressed in Xenopus oocytes, ethanol increased the ATP effect in an allosteric manner, and ethanol did not change the Hill coefficient or the maximum ATP effect (E_max). Zn²⁺ (1~300 μmol/L) reversibly enhanced the ATP-gated function of P2X3 receptor expressed in Xenopus oocytes, the combination of ethanol and Zn²⁺ led to a synergistic effect. Ethanol increased the maximum effect of Zn²⁺ on P2X3 receptor mediated ATP-gated current, which suggested that ethanol and Zn²⁺acted on different sites.

  Conclusion  This study reveals that ethanol and Zn²⁺ may act on different sites of P2X3 receptor, but the mechanism and site of ethanol acting on P2X receptor are not clear. In subsequent studies, chimeric method and site directed mutation can be used to identify and analyze the potential action sites of ethanol in P2X receptor.