title: Outward current in single smooth muscle cells of the guinea pig taenia coli.
abstract: In single myocytes of the guinea pig taenia coli, dispersed by enzymatic digestion, the late outward current is carried by K+. It has both a Ca2+-activated component and a voltage-dependent component which is resistant to external Co2+. The reversal potential is -84 mV, and the channel(s) for it are highly selective to K+. At 33 degrees C, the activation follows n2 kinetics, with a voltage-dependent time constant of 10.6 ms at 0 mV, which shortens to 1.7 ms at +70 mV. Deactivation follows a single-exponential time course, with a voltage-dependent time constant of 11 ms at -50 mV, which lengthens to 33 ms at -20 mV. During a 4.5-s maintained depolarization, IK inactivates, most of it into two exponential components, but there is a small noninactivating residue. It is surmised that during an action potential under physiological conditions, there is sufficient IK to cause repolarization.
authors.affiliation: Department of Pharmacology, State University of New York Downstate Medical Center, Brooklyn 11203.
authors.forename: Y
authors.initials: Y
authors.lastname: Yamamoto
authors.forename: S L
authors.initials: SL
authors.lastname: Hu
authors.forename: C Y
authors.initials: CY
authors.lastname: Kao
mesh_terms: D000200:Action Potentials; D000818:Animals; D002118:Calcium / Q000494:pharmacology; D003035:Cobalt / Q000494:pharmacology; D003106:Colon / Q000502:physiology; D006168:Guinea Pigs; D066298:In Vitro Techniques; D009130:Muscle, Smooth / Q000502:physiology*; D015221:Potassium Channels / Q000187:drug effects / Q000502:physiology
chemical_list: D015221:Potassium Channels; D003035:Cobalt; D002118:Calcium