Novel transient outward K+ current of mature murine hippocampal neurones.
Hippocampal neurones were freshly isolated from the brain of adult mice and voltage-dependent K+ currents were recorded with whole-cell patch-clamp technique. Three components of transient K+ current (IA) were isolated when analyzing data with exponential functions or treating neurones with a variety of voltage protocols and pharmacologic agents. Subtraction of the delayed rectifier current (IK) from the K+ currents elicited after prepulses to -120 mV of varying duration revealed fast (IAf) and slow (IAs) components with decay time constants of 45 +/- 8 and 612 +/- 140 ms, respectively; the corresponding time constants for the removal of inactivation were 12.3 and 189.6 ms. both tetraethylammonium and dendrotoxin selectively inhibited IAs. 4-Aminopyridine (4-AP) specifically blocked IAf and 40% of IAs with different affinities. Therefore, the properties of a 4-AP-resistant (IAsR) and 4-AP-sensitive (IAsS) component of IAs were compared. These data suggest that three distinct subtypes of K+ currents contribute to the IA of mature murine hippocampal neurones.
Li
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XY
Department of Pharmacology and Physiology, New Jersey Medical School (UMDNJ), 185 South Orange Avenue, Newark, NJ 07103-2714, USA.
McArdle
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JJ
D015761:4-Aminopyridine / Q000494:pharmacology; D000818:Animals; D004305:Dose-Response Relationship, Drug; D006624:Hippocampus / Q000502:physiology*; D051379:Mice; D009474:Neurons / Q000502:physiology; D015221:Potassium Channels / Q000187:drug effects / Q000502:physiology*; D013997:Time Factors
D015221:Potassium Channels; D015761:4-Aminopyridine