Effect of external potassium concentration on potassium uptake and potassium permeability of chicken enterocytes.
1. The effects of external potassium concentration on potassium uptake and potassium permeability have been investigated in isolated chicken enterocytes. 2. Ouabain-sensitive K+ uptake exhibited simple saturation kinetics with an apparent affinity constant, KT, of approximately, 1 mM K+. In the presence of ouabain, K+ uptake relates linearly with its external concentration, and the apparent diffusion constant, KD, was 1.3 nmol mg-1 protein mM-1 min-1. 3. Membrane potential, evaluated from the transmembrane TPP+ distribution ratio, was lower than the potassium equilibrium potential. 4. Estimated potassium permeability is decreased by low external potassium concentration and unaffected by high external potassium concentration.
Montero
M C
MC
Departamento de Fisiología y Biología Animal, Facultad de Farmacia, Universidad de Sevilla, Spain.
Ilundáin
A
A
D000818:Animals; D002463:Cell Membrane Permeability / Q000187:drug effects*; D002478:Cells, Cultured; D002645:Chickens; D007413:Intestinal Mucosa / Q000378:metabolism; D007422:Intestines / Q000166:cytology* / Q000187:drug effects; D007700:Kinetics; D008564:Membrane Potentials / Q000187:drug effects; D010042:Ouabain / Q000494:pharmacology; D011188:Potassium / Q000097:blood / Q000378:metabolism / Q000494:pharmacology*; D012414:Rubidium Radioisotopes; D013942:Thymine Nucleotides / Q000378:metabolism
D012414:Rubidium Radioisotopes; D013942:Thymine Nucleotides; D010042:Ouabain; C024157:thymidine 5'-triphosphate; D011188:Potassium