FUNCTIONAL INCORPORATION OF P-GLYCOPROTEIN INTO XENOPUS OOCYTE PLASMA-MEMBRANE FAILS TO ELICIT A SWELLING-EVOKED CONDUCTANCE

Microinjecton of Xenopus oocytes with P-glycoprotein-containing membra nes from multidrug resistant cells following a recently published proc edure resulted in the transplantation of the protein to the plasma mem brane of the oocytes and was confirmed by Western blot analysis. These oocytes showed a reduced intracellular accumulation of! daunomycin, w hen compared to uninjected oocytes or to those injected with membrane vesicles lacking P-glycoprotein, thus indicating that the protein had been incorporated in a transport-competent form. On the other hand, tr ansplantation of P-glycoprotein to the oocyte membrane did not signifi cantly change either the appearance or the properties of swelling-elic ited membrane conductance with respect to those determined in oocytes either uninjected or injected with membranes lacking P-glycoprotein. T hese results do not support a role for P-glycoprotein as a swelling ac tivated chloride channel. (C) 1997 Academic Press.