title: Potassium channels in Myxicola giant axons.
abstract: This article describes an initial step in the study of potassium ion (K+) channel properties and their role in the control of patterns of action potential frequency. The purpose of the study was to determine the effect of the K+ channel blocker 4-aminopyridine on the conductance of the K+ channels in Myxicola. If this pharmacologic agent modifies one or more of the multiple kinetic components of the K+ channel conductance, it may be expected to alter the physiological properties of normal and pathological nerve fibers. Experiments were performed on 19 internally perfused voltage-clamped Myxicola infundibulum giant axons. After accounting for the time-dependent accumulation of K+ in the surrounding periaxonal spaces, the K+ conductance activates biphasically. The external application of 4-aminopyridine (20 mmol/L) specifically blocks the fast component of activation of the K+ conductance.
mesh_terms: D015761:4-Aminopyridine; D000631:Aminopyridines / Q000494:pharmacology; D000818:Animals; D001369:Axons / Q000187:drug effects / Q000502:physiology*; D007473:Ion Channels / Q000502:physiology*; D009431:Neural Conduction / Q000187:drug effects; D011077:Polychaeta / Q000378:metabolism; D011188:Potassium / Q000378:metabolism*
chemical_list: D000631:Aminopyridines; D007473:Ion Channels; D015761:4-Aminopyridine; D011188:Potassium