Incorporation into a planar lipid bilayer of K channels from the luminal membrane of rabbit proximal tubule.
The presence of ionic channels at the apical membrane of rabbit proximal tubule cells was investigated by fusion of brush-border membrane vesicles (BBMV) with a planar lipid bilayer (PE/PC, 1:1). The BBMV obtained from native membranes showed poor fusogenic properties. The probability of vesicles fusion with a planar bilayer was, however, enhanced by preincubating the BBMV with liposomes made of azolectin. We report here the presence in BBMV preparations of two K(+)-selective channels of 65 pS and 40 pS, respectively, in asymmetrical 200 parallel 50 mM KCl solutions. The channel of 65 pS appeared highly selective to K+ over Na+ and Cl- ions, while the 40 pS channel discriminated poorly between K+ and Na+ with a permeability ratio PK/PNa = 4. The open probability Po of both channels was found to be voltage-independent within the potential range -60 mV to +60 mV. These K+ channels may be related to channels identified using other methods.
Bellemare
F
F
Département de physiologie, Faculté de médecine, Université de Montréal, Québec, Canada.
Morier
N
N
Sauvé
R
R
D000818:Animals; D002462:Cell Membrane / Q000378:metabolism / Q000502:physiology; D007687:Kidney Tubules, Proximal / Q000378:metabolism* / Q000502:physiology; D008051:Lipid Bilayers; D008564:Membrane Potentials; D008871:Microvilli / Q000378:metabolism / Q000502:physiology; D015221:Potassium Channels / Q000378:metabolism*; D011817:Rabbits
D008051:Lipid Bilayers; D015221:Potassium Channels