Thallium-201 uptake relates to membrane potential and potassium permeability in human glioma cells

Brain Res. 1989 Oct 23;500(1-2):30-6. doi: 10.1016/0006-8993(89)90296-5.

Abstract

The mechanism for 201Tl+ uptake was studied in cultured human glioma cell lines. Ouabain (1 mM) decreased the uptake at steady-state to 60%, but the rate of uptake was faster in the presence of ouabain. Addition of non-radioactive Tl+ (to a K+-free medium) decreased the uptake, but much less than expected for a system limited by the number of transport sites. Changes in K+ concentration of incubation medium affected the 201Tl+ uptake as predicted by the electrochemical equilibrium (Nernst equation). Using the uptake in isotonic KCl as a reference for membrane potential (0 mV), the calculated membrane potential was -75 mV in a medium with 3.0 mM K+. The Tl+-flux constants and the membrane permeabilities for Tl+ and K+ were calculated from the rate of uptake and from wash-out experiments. This is a new method for membrane potential and permeability studies in cell populations. The mechanism for 201Tl+ uptake is relevant for the clinical interpretation of 201Tl+ scintigraphy.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Humans
  • Membrane Potentials / drug effects
  • Ouabain / pharmacology
  • Potassium / metabolism*
  • Potassium / physiology
  • Thallium Radioisotopes / pharmacokinetics*
  • Tumor Cells, Cultured / drug effects
  • Tumor Cells, Cultured / metabolism
  • Tumor Cells, Cultured / physiology*
  • Valinomycin / pharmacology

Substances

  • Thallium Radioisotopes
  • Valinomycin
  • Ouabain
  • Potassium