Electrophysiological consequences of human IKs channel expression in adult murine heart

• Published in: American journal of physiology. Heart and circulatory physiology 2003-01, Vol.284 (1), p.H168-H175
• Main Authors: Chiello Tracy, Christine, Cabo, Candido, Coromilas, James, Kurokawa, Junko, Kass, Robert S, Wit, Andrew L
• Format: Article
• Language: English
• Subjects: Adrenergic beta-Agonists - pharmacology; Aging - physiology; Animals; Blood Pressure - drug effects; Cardiac Pacing, Artificial; Delayed Rectifier Potassium Channels; Electrophysiology; Female; Heart Rate; Humans; Isoproterenol - pharmacology; Male; Mice; Mice, Transgenic - genetics; Myocardium - metabolism; Potassium Channels - physiology; Potassium Channels, Voltage-Gated; Refractory Period, Electrophysiological - drug effects; Tachycardia, Ventricular - etiology; Tachycardia, Ventricular - physiopathology; Ventricular Function - drug effects
• ISSN: 0363-6135; 1522-1539
• DOI: 10.1152/ajpheart.00661.2002

1  Departments of Pharmacology and 2  Medicine and 3  Center for Molecular Therapeutics, Columbia University, College of Physicians and Surgeons, New York, New York 10032 We expressed human delayed rectifier K + cardiac current ( I Ks ) channels in the murine heart, which lacks native I Ks , to determine their electrophysiological role. Mice expressing human I Ks channels were anesthetized, and an electrocardiogram and monophasic action potentials (MAP) recorded from the left ventricle. Sinus rate was not different between wild-type mice (WT) and transgenic mice (TG). Infusion of isoproterenol accelerated WT heart rate but not TG. Lack of TG sinus rate responsiveness may have resulted from accumulated outward current in I Ks channels in sinus node. Ventricular MAP duration of TG mice to 50% repolarization (APD 50 ) during ventricular pacing was shorter than WT, likely resulting from outward current through I Ks channels. TG APD 50 showed enhanced responsiveness (shortening) to isoproterenol compared with WT. Ventricular tachyarrhythmias were initiated in TG mice by programmed stimulation but not in WT and were accelerated by isoproterenol. I Ks channels impart -adrenergic sensitivity to the ventricles and may be responsible for ventricular tachyarrhythmias. arrhythmia; -adrenergic; repolarization; heart rate; delayed rectifier K + cardiac current