Modulation By PH Of Rat P2X₄ Receptors Expressed In Xenopus Oocytes

partâ… Establishment of heterologous expression model of P2X₄ receptorObjective: To transplant the P2X₄cDNA which was cloned from rat superior cervical ganglia into mRNA and record the current of P2X₄ receptor expressed on Xenopus oocytes.Methods: mRNA of P2X₄ receptor was transcribed from cDNA , which was cloned in the vector pcDNA3. Each oocyte of mature Xenopus laevis was injected with transcribed mRNA in vivo and incubated at room temperature for 48～72h. Recording the current induced by ATP with Two-electrode voltage clamp technique tested the function of the expressed P2X₄ cDNA.Results: The transporter current could be observed in Ringer′s solution containing ATP,and the ATP induced current was concentration-dependent. PPADS and suramin had little or no effect on ATP-avtivated current on Xenopus oocytes mediated by P2X₄ receptor cloned from rat superior cervical ganglia.Conclusion: The results demonstrate that the heterologous expression product on Xenopus oocytes is P2X₄ receptor.Partâ…¡Modulation by pH of rat P2X₄ receptors expressed in Xenopus oocytesObjective:To investigate the charecterestics and the modulatory effect of H+ on ATP-activated current(IATP) on P2X₄ receptors cloned from rat superior cervical ganglion.Methods:Two-electrode voltage clamp technique was used to record the the ATP-activated current in healthy Xenopus oocytes expressing P2X₄ receptor.Results: The experimental results showed that all the healthy oocytes expressing P2X₄ receptor appeared to be sensitive to ATP (10-4mol/l) with an characteristic current in a concentration-dependent manner.The current showed slow desensitization.Maximal responses recorded reached up to 5μA at 300μM ATP,reproducible responses could be obtained.The amplitude of IATP decreased when pH of extracellular fluid was adjusted to 7.4 or 5.8.The respective ATPEC50 values for pH 6.3, pH 7.4 were11.2±0.4μM,9.1±0.4μM.Conclusion:The results suggested that pH decreasing inhibited the ATP-activated current mediated by rat P2X₄ receptors expressed in Xenopus oocytes.Partâ…¢Recent advances of P2X₄ receptorsThe P2X receptors comprise a family of ligand-gated cation channels which are opended by the binding of extracelluar ATP.Seven different genes encoding P2X receptors have been clonded,The P2X₄ is the most abundant P2X subunit in the brain ,these receptors could be important in the central nervous systems and the peripheral nervous system .The characteristics ,modulation ,distribution ,biological function of P2X₄ receptors are described.