Delayed potassium current and non-specific outward current in pyramidal neurones acutely dissociated from rat hippocampus.
The electrical property of delayed K+ currents (IKD) was studied in pyramidal neurones freshly isolated from the rat hippocampal CA1 region. The IKD was separated pharmacologically from other membrane currents. Activation and inactivation processes of the IKD were highly voltage-dependent in the potential range between -30 and +20 mV. The steady-state inactivation of IKD was observed at -100 mV or more positive potentials. The potential for half steady-state inactivation was -65 mV. The IKD was fully inactivated around -20 mV. Reactivation of IKD consisted of two exponential components. After pharmacological suppression of IKD, the small amount of residual voltage-dependent outward current (one-fifteenth to one-twentieth of IKD amplitude) was observed. The current kinetics was similar to that of IKD and greatly reduced by substitution of internal K+ with N-methyl-D-glucamine+. It was concluded that the properties of IKD was basically similar to those of IKD in other excitable tissues and that the residual current might be non-specific outward current.
Oyama
Y
Y
Department of Neurophysiology, Tohoku University School of Medicine, Sendai, Japan.
Harata
N
N
Akaike
N
N
D015761:4-Aminopyridine / Q000494:pharmacology; D000818:Animals; D004558:Electric Stimulation; D006624:Hippocampus / Q000502:physiology*; D066298:In Vitro Techniques; D007700:Kinetics; D007811:Lanthanum / Q000494:pharmacology; D008564:Membrane Potentials / Q000187:drug effects; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D015221:Potassium Channels / Q000187:drug effects / Q000502:physiology*; D011712:Pyramidal Tracts / Q000502:physiology*; D051381:Rats; D019789:Tetraethylammonium; D013757:Tetraethylammonium Compounds / Q000494:pharmacology; D013779:Tetrodotoxin / Q000494:pharmacology
D015221:Potassium Channels; D013757:Tetraethylammonium Compounds; D013779:Tetrodotoxin; D019789:Tetraethylammonium; D007811:Lanthanum; D015761:4-Aminopyridine