Non-selective cation channels in basolateral-membrane vesicles from pars recta of rabbit kidney proximal tubule.
The characteristics of 86Rb+ fluxes through conductive channels in basolateral-membrane vesicles isolated from pars recta of rabbit kidney proximal tubule were investigated. In RbCl-, KCl- and NaCl-loaded vesicles a transient and almost equal accumulation of 86Rb+ was observed. The uptakes of 86Rb+ were inhibited to the same extent by 10 mM-BaCl2 in all loadings. The accumulation was driven by an electrical diffusion potential. The 86Rb+ flux was dependent on intravesicular Ca2+. Increasing concentrations of Ca2+ gradually decreased the 86Rb+ uptake. At 10 microM-Ca2+ the radioisotope flux was below 20% of control. The vesicles containing the channel showed very low selectivity among the univalent cations K+, Rb+, Li+, Na+ and choline+.
Institute of Medical Biochemistry, University of Aarhus, Denmark.
J
J
Blokkebak-Poulsen
M I
MI
Sheikh
C
C
Jacobsen
D000818:Animals; D001464:Barium / Q000494:pharmacology; D002118:Calcium / Q000494:pharmacology; D002414:Cations, Monovalent; D002462:Cell Membrane / Q000378:metabolism; D007473:Ion Channels / Q000187:drug effects / Q000378:metabolism*; D007687:Kidney Tubules, Proximal / Q000378:metabolism*; D007700:Kinetics; D011817:Rabbits; D012413:Rubidium / Q000378:metabolism
D002414:Cations, Monovalent; D007473:Ion Channels; D001464:Barium; D012413:Rubidium; D002118:Calcium