P2X7 PURINOCEPTOR EXPRESSION IN XENOPUS OOCYTES IS NOT SUFFICIENT TO PRODUCE A PORE-FORMING P2Z-LIKE PHENOTYPE

The purinergic rP2X7 receptor expressed in a number of heterologous sy stems not only functions as a cation channel but also gives rise to a P2Z-like response, i.e. a reversible membrane permeabilization that al lows the passage of molecules with molecular masses of greater than or equal to 300 Da, We investigated the properties of rP2X7 receptors ex pressed in Xenopus oocytes, In two-electrode voltage-clamp experiments , ATP or BzATP caused inward currents that were abolished or greatly d iminished when NMDG(+) or choline(+) replaced Na+ as the principal ext ernal cation, In fluorescent dye experiments, BzATP application did no t result in entry of the fluorophore YO-PRO-1(2+), Thus, rP2X7 express ion in Xenopus oocytes does not by itself give rise to the pore-formin g P2Z phenotype, suggesting that ancillary factors are involved. (C) 1 997 Federation of European Biochemical Societies.