Carvedilol targets human K2P3.1 (TASK1) K+ leak channels

• Published in: British journal of pharmacology Vol. 163; no. 5; pp. 1099 - 1110
• Main Authors: Staudacher, K, Staudacher, I, Ficker, E, Seyler, C, Gierten, J, Kisselbach, J, Rahm, A‐K, Trappe, K, Schweizer, PA, Becker, R, Katus, HA, Thomas, D
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01-07-2011; Nature Publishing Group; Blackwell Science Inc
• Subjects: antiarrhythmic drug; background potassium current; Biological and medical sciences; cardiac arrhythmia; Cardiac dysrhythmias; Cardiology. Vascular system; carvedilol; cellular excitability; Heart; K2P channel; leak current; Medical sciences; membrane potential; Pharmacology. Drug treatments; Research Papers; Heart; Vasodilator agent; Targeting; Arrhythmia; Electrophysiology; α1-Adrenergic receptor; channel; Cardiovascular disease; β2-Adrenergic receptor; Ionic channel; Ionic current; K; Inorganic element; antiarrhythmic drug; Target; Alpha blocking agent; β1-Adrenergic receptor; Heart disease; leak current; cellular excitability; Antagonist; Membrane potential; Human; Drug; cardiac arrhythmia; Excitability; Antiarrhythmic agent; In vitro; background potassium current; Carvedilol; Antihypertensive agent; Circulatory system; Potassium; Beta blocking agent
• ISSN: 0007-1188; 1476-5381
• DOI: 10.1111/j.1476-5381.2011.01319.x

BACKGROUND AND PURPOSE Human K2P3.1 (TASK1) channels represent potential targets for pharmacological management of atrial fibrillation. K2P channels control excitability by stabilizing membrane potential and by expediting repolarization. In the heart, inhibition of K2P currents by class III antiarrhythmic drugs results in action potential prolongation and suppression of electrical automaticity. Carvedilol exerts antiarrhythmic activity and suppresses atrial fibrillation following cardiac surgery or cardioversion. The objective of this study was to investigate acute effects of carvedilol on human K2P3.1 (hK2P3.1) channels.
EXPERIMENTAL APPROACH Two‐electrode voltage clamp and whole‐cell patch clamp electrophysiology was used to record hK2P3.1 currents from Xenopus oocytes, Chinese hamster ovary (CHO) cells and human pulmonary artery smooth muscle cells (hPASMC).
KEY RESULTS Carvedilol concentration‐dependently inhibited hK2P3.1 currents in Xenopus oocytes (IC50= 3.8 µM) and in mammalian CHO cells (IC50= 0.83 µM). In addition, carvedilol sensitivity of native IK2P3.1 was demonstrated in hPASMC. Channels were blocked in open and closed states in frequency‐dependent fashion, resulting in resting membrane potential depolarization by 7.7 mV. Carvedilol shifted the current–voltage (I–V) relationship by −6.9 mV towards hyperpolarized potentials. Open rectification, characteristic of K2P currents, was not affected.
CONCLUSIONS AND IMPLICATIONS The antiarrhythmic drug carvedilol targets hK2P3.1 background channels. We propose that cardiac hK2P3.1 current blockade may suppress electrical automaticity, prolong atrial refractoriness and contribute to the class III antiarrhythmic action in patients treated with the drug.