Negative slope conductance due to a persistent subthreshold sodium current in cat neocortical neurons in vitro.
The voltage dependent ionic currents of large layer V neurons of cat sensory/motor cortex were examined in an in vitro slice preparation using a single-microelectrode voltage clamp. These cells exhibit a persistent inward current in a voltage range below spike threshold. This inward current is responsible for the increase of input resistance upon depolarization seen in these cells in response to a constant current pulse and is activated at the same voltages traversed by the membrane potential between spikes during rhythmic firing. The inward current appears to be a persistent sodium current, since it is unaffected by extracellular Ba2+ or Co2+ but is blocked by extracellular TTX or intracellular QX314.
D000818:Animals; D002415:Cats; D002540:Cerebral Cortex / Q000502:physiology*; D007473:Ion Channels / Q000502:physiology*; D008564:Membrane Potentials; D009044:Motor Cortex / Q000502:physiology; D009046:Motor Neurons / Q000502:physiology; D009431:Neural Conduction; D009474:Neurons / Q000502:physiology; D011712:Pyramidal Tracts / Q000502:physiology; D012964:Sodium / Q000502:physiology*; D013003:Somatosensory Cortex / Q000502:physiology
D007473:Ion Channels; D012964:Sodium