Comparison between the responses mediated by endogenous and expressed ATP-and GABA-receptors in Xenopus laevis oocytes

Objective: To study the comparison between the responses mediated by endogenous and expressed ATP-and GABA-receptors in Xenopus laevis oocytes. Methods: The two-electrode voltage-clamp technique was used. Results: (1) Zn²⁺ (10^-5 mol/L) could potentiate the current responses mediated by expressed P2X2 and P2X4 receptors in oocytes; (2) GABA-activated current in the oocytes which were injected mRNA of chicken brain could be blocked by bicuculline (10^-5 mol/L), a selective GABA_A receptor antagonist; (3) GABA-activated current mediated by ρ1 subunit of human retina could not be blocked by bicuculline (10^-5 mol/L), but it could be abolished by picrotoxin (10^-5 mol/L); (4) there were three types ATP-activated current in the follicular oocytes, while there was only one type GABA-activated current; (5) there were no responses mediated by ATP or GABA receptors in the defollicular oocytes. Conclusion: There exist endogenous GABA_A and GABAc receptors and ATP receptors in the follicular oocytes. The current responses mediated by exogenous GABA receptors and P2X2 and P2X4 receptors are different from that mediated by endogenous GABA receptors and ATP receptors.