Relation between BK-α/β4-mediated potassium secretion and ENaC-mediated sodium reabsorption Academic Article uri icon

Overview

MeSH Major

  • Epithelial Sodium Channels
  • Large-Conductance Calcium-Activated Potassium Channel alpha Subunits
  • Large-Conductance Calcium-Activated Potassium Channel beta Subunits
  • Nephrons
  • Sodium

abstract

  • The large-conductance, calcium-activated BK-α/β4 potassium channel, localized to the intercalated cells of the distal nephron, mediates potassium secretion during high-potassium, alkaline diets. Here we determine whether BK-α/β4-mediated potassium transport is dependent on epithelial sodium channel (ENaC)-mediated sodium reabsorption. We maximized sodium-potassium exchange in the distal nephron by feeding mice a low-sodium, high-potassium diet. Wild-type and BK-β4 knockout mice were maintained on a low-sodium, high-potassium, alkaline diet or a low-sodium, high-potassium, acidic diet for 7-10 days. Wild-type mice maintained potassium homeostasis on the alkaline, but not acid, diet. BK-β4 knockout mice could not maintain potassium homeostasis on either diet. During the last 12 h of diet, wild-type mice on either a regular, alkaline, or an acid diet, or knockout mice on an alkaline diet, were administered amiloride (an ENaC inhibitor). Amiloride enhanced sodium excretion in all wild-type and knockout groups to similar values; however, amiloride diminished potassium excretion by 59% in wild-type but only by 33% in knockout mice on an alkaline diet. Similarly, amiloride decreased the trans-tubular potassium gradient by 68% in wild-type but only by 42% in knockout mice on an alkaline diet. Amiloride treatment equally enhanced sodium excretion and diminished potassium secretion in knockout mice on an alkaline diet and wild-type mice on an acid diet. Thus, the enhanced effect of amiloride on potassium secretion in wild-type compared to knockout mice on the alkaline diet clarify a BK- α/β4-mediated potassium secretory pathway in intercalated cells driven by ENaC-mediated sodium reabsorption linked to bicarbonate secretion.

publication date

  • January 2014

Research

keywords

  • Academic Article

Identity

Language

  • eng

PubMed Central ID

  • PMC4077913

Digital Object Identifier (DOI)

  • 10.1038/ki.2014.14

PubMed ID

  • 24573316

Additional Document Info

start page

  • 139

end page

  • 45

volume

  • 86

number

  • 1