A mutant of Paramecium with increased relative resting potassium permeability

J Neurobiol. 1976 Jul;7(4):325-38. doi: 10.1002/neu.480070405.

Abstract

Fast-2, a membrane mutant of Paramecium aurelia, is due to a single-gene mutation and has behavioral abnormalities. Intracellular recordings through changes of external solutions were made. The mutant membrane hyperpolarized when it encountered solutions with low K+ concentration. This hyperpolarization and other associated activities were best observed in Ca- or Na-solutions devoid of K+. Membrane potential was plotted against the concentration of K+ (0.5 to 16 mM) in solutions of fixed Na+ or Ca++ concentration. The slopes of the curves for the mutant membrane were steeper than those for the wild type at the lower concentrations of K+. Inclusion of 2 mM tetraethylammonium chloride (TEA-Cl) counteracted the mutational effects. Spontaneous action potentials in Ba-solution and the electrically evoked action potentials in various solutions are normal in this mutant. We conclude that the resting permeability to K+ relative to the permeabilities to Na+ and Ca++ has been increased by the mutation.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Barium / pharmacology
  • Calcium / pharmacology
  • Cell Membrane Permeability / drug effects*
  • Electric Conductivity
  • Electric Stimulation
  • Evoked Potentials / drug effects
  • Membrane Potentials / drug effects
  • Mutation
  • Paramecium / drug effects
  • Paramecium / physiology*
  • Potassium / metabolism*
  • Sodium / pharmacology
  • Tetraethylammonium Compounds / pharmacology

Substances

  • Tetraethylammonium Compounds
  • Barium
  • Sodium
  • Potassium
  • Calcium