Development of new Kir2.1 channel openers from propafenone analogues

Abstract

Background and Purposes: Reduced inward rectifier potassium channel (Kir2.1) functioning is associated with heart failure and may cause Andersen-Tawil Syndrome, among others characterized by ventricular arrhythmias. Most heart failure or Andersen–Tawil Syndrome patients are treated with β-adrenoceptor antagonists (β-blockers) or sodium channel blockers; however, these do not specifically address the inward rectifier current (IK1) nor aim to improve resting membrane potential stability. Consequently, additional pharmacotherapy for heart failure and Andersen–Tawil Syndrome treatment would be highly desirable. Acute propafenone treatment at low concentrations enhances IK1 current, but it also exerts many off-target effects. Therefore, discovering and exploring new IK1-channel openers is necessary. Experimental Approach: Effects of propafenone and 10 additional propafenone analogues were analysed. Currents were measured by single-cell patch-clamp electrophysiology. Kir2.1 protein expression levels were determined by western blot analysis and action potential characteristics were further validated in human-induced pluripotent stem cells–derived cardiomyocytes (hiPSC-CMCs). Molecular docking was performed to obtain detailed information on drug-channel interactions. Key Results: Analogues GPV0019, GPV0057 and GPV0576 strongly increased the outward component of IK1 while not affecting the Kir2.1 channel expression levels. GPV0057 did not block IKr at concentrations below 0.5 μmol L−1 nor NaV1.5 current below 1 μmol L−1. Moreover, hiPSC-CMC action potential duration was also not affected by GPV0057 at 0.5 and 1 μmol L−1. Structure analysis indicates a mechanism by which GPV0057 might enhance Kir2.1 channel activation. Conclusion and Implications: GPV0057 has a strong efficiency towards increasing IK1, which makes it a good candidate to address IK1 deficiency-associated diseases.