title: Role of slow delayed rectifying potassium current in dynamics of repolarization and electrical memory in swine ventricles.
abstract: Dynamics of repolarization, quantified as restitution and electrical memory, impact conduction stability. Relatively less is known about role of slow delayed rectifying potassium current, I(Ks), in dynamics of repolarization and memory compared to the rapidly activating current I(Kr). Trans-membrane potentials were recorded from right ventricular tissues from pigs during reduction (chromanol 293B) and increases in I(Ks) (mefenamic acid). A novel pacing protocol was used to explicitly control diastolic intervals to quantify memory. Restitution hysteresis, a consequence of memory, increased after chromanol 293B (loop thickness and area increased 27 and 38 %) and decreased after mefenamic acid (52 and 53 %). Standard and dynamic restitutions showed an increase in average slope after chromanol 293B and a decrease after mefenamic acid. Increase in slope and memory are hypothesized to have opposite effects on electrical stability; therefore, these results suggest that reduction and enhancement of I(Ks) likely also have offsetting components that affect stability.
authors.affiliation: Department of Biomedical Engineering, University of Kentucky, Lexington, KY, USA.
authors.forename: Linyuan
authors.initials: L
authors.lastname: Jing
authors.forename: Kathleen
authors.initials: K
authors.lastname: Brownson
authors.forename: Abhijit
authors.initials: A
authors.lastname: Patwardhan
mesh_terms: D000200:Action Potentials; D000818:Animals; D000889:Anti-Arrhythmia Agents / Q000494:pharmacology; D001145:Arrhythmias, Cardiac / Q000209:etiology / Q000378:metabolism* / Q000503:physiopathology / Q000517:prevention & control; D002304:Cardiac Pacing, Artificial; D002839:Chromans / Q000494:pharmacology; D051668:Delayed Rectifier Potassium Channels / Q000187:drug effects / Q000378:metabolism*; D006329:Heart Conduction System / Q000187:drug effects / Q000378:metabolism* / Q000503:physiopathology; D006352:Heart Ventricles / Q000187:drug effects / Q000378:metabolism* / Q000503:physiopathology; D066298:In Vitro Techniques; D007700:Kinetics; D008528:Mefenamic Acid / Q000494:pharmacology; D026902:Potassium Channel Blockers / Q000494:pharmacology; D013449:Sulfonamides / Q000494:pharmacology; D034421:Sus scrofa
chemical_list: D000889:Anti-Arrhythmia Agents; D002839:Chromans; D051668:Delayed Rectifier Potassium Channels; D026902:Potassium Channel Blockers; D013449:Sulfonamides; C103474:6-cyano-4-(N-ethylsulfonyl-N-methylamino)-3-hydroxy-2,2-dimethylchromane; D008528:Mefenamic Acid