title: Effect of 4-aminopyridine on potassium permeability of canine tracheal smooth muscle cell membrane.
abstract: Effect of 4-aminopyridine (4-AP) on the potassium permeability of the cell membrane of canine tracheal smooth muscle was investigated using 86Rb-efflux. The 86Rb-efflux from the strip was remarkably increased by 20 mM 4-AP in normal physiological solution in the presence of 1 microM atropine. In high potassium and chloride deficient solution, 4-AP (0.3-20 mM) decreased the rate of 86Rb-efflux in a dose-dependent manner. This finding indicates that 4-AP interacted with a single class of site of action in depolarized tracheal smooth muscle. The maximum decrease in 86Rb-efflux and the inhibitory dissociation constant of 4-AP were 42.3% and 1.49 mM, respectively. 4-AP had an inhibitory effect on the K permeability of the cell membrane of canine tracheal smooth muscle, and it seemed to interact with the same site of action of tetraethylammonium (TEA), but was less effective than TEA.
mesh_terms: D015761:4-Aminopyridine; D000631:Aminopyridines / Q000494:pharmacology*; D000818:Animals; D001285:Atropine / Q000494:pharmacology; D002463:Cell Membrane Permeability / Q000187:drug effects*; D004285:Dogs; D005711:Gallopamil / Q000494:pharmacology; D066298:In Vitro Techniques; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects / Q000378:metabolism*; D011188:Potassium / Q000378:metabolism*; D011868:Radioisotopes; D012413:Rubidium; D019789:Tetraethylammonium; D013757:Tetraethylammonium Compounds / Q000494:pharmacology; D013779:Tetrodotoxin / Q000494:pharmacology; D014132:Trachea / Q000378:metabolism
chemical_list: D000631:Aminopyridines; D011868:Radioisotopes; D013757:Tetraethylammonium Compounds; D005711:Gallopamil; D013779:Tetrodotoxin; D019789:Tetraethylammonium; D001285:Atropine; D015761:4-Aminopyridine; D012413:Rubidium; D011188:Potassium