Click here to close
Hello! We notice that you are using Internet Explorer, which is not supported by Xenbase and may cause the site to display incorrectly.
We suggest using a current version of Chrome,
FireFox, or Safari.
K+ recirculation in A6 cells at increased Na+ transport rates.
Granitzer M, Nagel W, Crabbé J.
???displayArticle.abstract???
Homocellular regulation of K+ at increased transcellular Na+ transport implies an increase in K+ exit to match the intracellular K+ load. Increased K+ conductance, gK, was suggested to account for this gain. We tested whether such a mechanism is operational in A6 monolayers. Na+ transport was increased from 5.1 +/- 1.0 microA/cm2 to 20.7 +/- 1.3 microA/cm2 by preincubation with 0.1 mumol/l dexamethasone for 24 h. Basolateral K+ conductances were derived from transference numbers of K+, tK, and basolateral membrane conductances, gb, using conventional microelectrodes and circuit analysis with application of amiloride. Activation of Na+ transport induced an increase in gb from 0.333 +/- 0.067 mS/cm2 to 1.160 +/- 0.196 mS/cm2 and tK was reduced to 0.22 +/- 0.01 from a value of 0.70 +/- 0.05 in untreated control tissues. As a result, gK remained virtually unchanged at increased Na+ transport rates. The increase in gb after dexamethasone was due to activation of a conductive leak pathway presumably for Cl-. Increased K+ efflux, IK, was a consequence of the larger driving force for K+ exit due to depolarization at an elevated Na+ transport rate. The relationship between calculated K+ fluxes and Na+ transport rate, measured as the Isc, is described by the linear function IK = 0.624 x INa -0.079, which conforms with a stoichiometry 2:3 for the fluxes of K+ and Na+ in the Na+/K(+)-ATPase pathway. Our data show that homocellular regulation of K+ in A6 cells is not due to up-regulation of gK.
Filipovic,
A calcium-permeable stretch-activated cation channel in renal proximal tubule.
1991, Pubmed,
Xenbase
Filipovic,
A calcium-permeable stretch-activated cation channel in renal proximal tubule.
1991,
Pubmed
,
Xenbase Granitzer,
Apical and basolateral conductance in cultured A6 cells.
1991,
Pubmed
,
Xenbase Granitzer,
Basolateral membrane conductance in A6 cells: effect of high sodium transport rate.
1992,
Pubmed Granitzer,
Voltage dependent membrane conductances in cultured renal distal cells.
1991,
Pubmed
,
Xenbase Hamilton,
A non-selective cation channel in the apical membrane of cultured A6 kidney cells.
1990,
Pubmed Higgins,
Electrical properties of amphibian urinary bladder epithelia. II. The cell potential profile in necturus maculosus.
1977,
Pubmed Horisberger,
Apical and basolateral membrane conductances in the TBM cell line.
1991,
Pubmed Hunter,
Potassium-selective channels in the basolateral membrane of single proximal tubule cells of frog kidney.
1991,
Pubmed Hunter,
Potassium channels along the nephron.
1986,
Pubmed Illek,
Aldosterone regulation of basolateral potassium channels in alveolar epithelium.
1990,
Pubmed
,
Xenbase Kawahara,
Potassium channels in Necturus proximal tubule.
1987,
Pubmed Kolb,
Characterization of a Ca-dependent maxi K channel in the apical membrane of a cultured renal epithelium (JTC-12.P3).
1986,
Pubmed Lang,
Electrophysiology of sodium-coupled transport in proximal renal tubules.
1986,
Pubmed Lang,
Potassium channels in renal epithelial transport regulation.
1992,
Pubmed Merot,
Two types of K+ channels in the apical membrane of rabbit proximal tubule in primary culture.
1989,
Pubmed Nagel,
Mechanism of action of aldosterone on active sodium transport across toad skin.
1980,
Pubmed Nakanishi,
Survey of osmolytes in renal cell lines.
1988,
Pubmed Schultz,
Homocellular regulatory mechanisms in sodium-transporting epithelia: avoidance of extinction by "flush-through".
1981,
Pubmed Sugimoto,
Immunohistochemical study of a rat membrane protein which induces a selective potassium permeation: its localization in the apical membrane portion of epithelial cells.
1990,
Pubmed
,
Xenbase Takumi,
Cloning of a membrane protein that induces a slow voltage-gated potassium current.
1988,
Pubmed
,
Xenbase Thomas,
Time-dependent apical membrane K+ and Na+ selectivity in cultured kidney cells.
1987,
Pubmed
