Depression of spike adaptation and afterhyperpolarization by 4-aminopyridine in hippocampal neurons.
In guinea pig hippocampal slices, 4-aminopyridine (4-AP) in concentrations of 100-500 microM reduced the adaptation of CA3 pyramidal neurons to depolarizing stimuli, resulting in a prolongation of repetitive firing during injection of long-lasting depolarizing currents. Concurrently, there was a decrease in the 'sag' of potential after spike bursts. Furthermore, 4-AP decreased or abolished the hyperpolarizing potential (the afterhyperpolarization) which normally followed repetitive firing of the neurons. The findings suggest that 4-AP could interfere with the Ca2+-activated K+ current in hippocampal CA3 pyramidal neurons.
D015761:4-Aminopyridine; D000200:Action Potentials / Q000187:drug effects; D000222:Adaptation, Physiological / Q000187:drug effects; D000631:Aminopyridines / Q000494:pharmacology*; D000818:Animals; D004558:Electric Stimulation; D006168:Guinea Pigs; D006624:Hippocampus / Q000187:drug effects / Q000502:physiology*; D008564:Membrane Potentials / Q000187:drug effects; D009433:Neural Inhibition / Q000187:drug effects*
D000631:Aminopyridines; D015761:4-Aminopyridine