title: Effects of dietary K on cell-surface expression of renal ion channels and transporters.
abstract: Changes in apical surface expression of ion channels and transporters in the superficial rat renal cortex were assessed using biotinylation and immunoblotting during alterations in dietary K intake. A high-K diet increased, and a low-K diet decreased, both the overall and surface abundance of the β- and γ-subunits of the epithelial Na channel (ENaC). In the case of γ-ENaC, the effect was specific for the 65-kDa cleaved form of the protein. The overall amount of α-ENAC was also increased with increasing K intake. The total expression of the secretory K(+) channels (ROMK) increased with a high-K diet and decreased with a low-K diet. The surface expression of ROMK increased with high K intake but was not significantly altered by a low-K diet. In contrast, the amounts of total and surface protein representing the thiazide-sensitive NaCl cotransporter (NCC) decreased with increasing K intake. We conclude that modulation of K(+) secretion in response to changes in dietary K intake involves changes in apical K(+) permeability through regulation of K(+) channels and in driving force subsequent to alterations in both Na delivery to the distal nephron and Na(+) uptake across the apical membrane of the K(+) secretory cells.
authors: Dept. Physiology and Biophysics, Weill Medical College of Cornell Univ., 1300 York Ave., New York, NY 10065, USA.
authors: Gustavo
authors: G
authors: Frindt
authors: Lawrence G
authors: LG
authors: Palmer
mesh_terms: D000818:Animals; D053503:Epithelial Sodium Channels / Q000187:drug effects / Q000378:metabolism*; D005260:Female; D007672:Kidney Cortex / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D023421:Models, Animal; D009399:Nephrons / Q000378:metabolism; D009865:Oocytes / Q000378:metabolism; D015221:Potassium Channels / Q000187:drug effects / Q000378:metabolism*; D024661:Potassium Channels, Inwardly Rectifying / Q000378:metabolism; D017419:Potassium, Dietary / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012964:Sodium / Q000378:metabolism; D049992:Sodium Chloride Symporters / Q000187:drug effects / Q000378:metabolism*; D014982:Xenopus laevis
chemical_list: D053503:Epithelial Sodium Channels; C510692:Kcnj1 protein, rat; D015221:Potassium Channels; D024661:Potassium Channels, Inwardly Rectifying; D017419:Potassium, Dietary; D049992:Sodium Chloride Symporters; D012964:Sodium