Swelling-activated chloride and potassium conductance in primary cultures of mouse proximal tubules. Implication of KCNE1 protein.
Volume-sensitive chloride and potassium currents were studied, using the whole-cell clamp technique, in cultured wild-type mouse proximal convoluted tubule (PCT) epithelial cells and compared with those measured in PCT cells from null mutant kcne1 -/- mice. In wild-type PCT cells in primary culture, a Cl- conductance activated by cell swelling was identified. The initial current exhibited an outwardly rectifying current-voltage (I-V) relationship, whereas steady-state current showed decay at depolarized membrane potentials. The ion selectivity was I- > Br- > Cl- > > gluconate. This conductance was sensitive to 1 mM 4,4'-Diisothiocyanostilbene-2,2'-disulfonic acid (DIDS), 0.1 mM 5-nitro-2-(3-phenylpropylamino)benzoic acid (NPPB) and 1 mM diphenylamine-2-carboxylate (DPC). Osmotic stress also activated K+ currents. These currents are time-independent, activated at depolarized potentials, and inhibited by 0.5 mM quinidine, 5 mM barium, and 10 microM clofilium but are insensitive to 1 mM tetraethylammonium (TEA), 10 nM charybdotoxin (CTX), and 10 microM 293B. In contrast, the null mutation of kcne1 completely impaired volume-sensitive chloride and potassium currents in PCT. The transitory transfection of kcne1 restores both Cl- and K+ swelling-activated currents, confirming the implication of KCNE1 protein in the cell-volume regulation in PCT cells in primary cultures.
Barrière
H
H
UMR CNRS 6548, Université de Nice-Sophia Antipolis, 06108 Nice Cedex 2, France.
Rubera
I
I
Belfodil
R
R
Tauc
M
M
Tonnerieux
N
N
Poujeol
C
C
Barhanin
J
J
Poujeol
P
P
D000818:Animals; D048429:Cell Size; D002478:Cells, Cultured; D018118:Chloride Channels / Q000187:drug effects / Q000502:physiology; D002713:Chlorine / Q000378:metabolism*; D004553:Electric Conductivity; D007038:Hypotonic Solutions / Q000494:pharmacology; D007687:Kidney Tubules, Proximal / Q000166:cytology* / Q000187:drug effects / Q000502:physiology*; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology*; D051379:Mice; D018345:Mice, Knockout; D009995:Osmosis / Q000187:drug effects / Q000502:physiology; D009997:Osmotic Pressure / Q000187:drug effects; D011188:Potassium / Q000378:metabolism*; D015221:Potassium Channels / Q000172:deficiency / Q000187:drug effects / Q000502:physiology*; D024642:Potassium Channels, Voltage-Gated
D018118:Chloride Channels; D007038:Hypotonic Solutions; D015221:Potassium Channels; D024642:Potassium Channels, Voltage-Gated; C059983:potassium channel protein I(sk); D002713:Chlorine; D011188:Potassium