A potassium conductance activated by hyperpolarization in paramecium.
Voltage clamp studies show that the wild-type membrane of Paramecium tetraurelia contains a conductance component which is sensitive to hyperpolarization. This component manifests itself as "anomalous", or "inward going", rectification of membrane voltage in response to applied constant current pulses and as a "hyperpolarizing spike" when no K is added to the external solution (Y. Satow, C. Kung, 1977. J. Comp. Physiol. 119:99). Like the conductances which underlie anomalous rectification in other cells, the hyperpolarization-sensitive conductance in Paramecium is specific for K, and the magnitude of the voltage-dependent conductance change depends not only on voltage but also on external potassium concentration. The internal potassium ion concentration of Paramecium is calculated to be between 17 and 18mM.
D000818:Animals; D002463:Cell Membrane Permeability; D004553:Electric Conductivity; D007473:Ion Channels / Q000502:physiology*; D008564:Membrane Potentials; D010247:Paramecium / Q000502:physiology*; D011188:Potassium / Q000502:physiology*
D007473:Ion Channels; D011188:Potassium