Ajmaline blocks INa and IKr without eliciting differences between Brugada syndrome patient and control human pluripotent stem cell-derived cardiac clusters

Stem Cell Res. 2017 Dec:25:233-244. doi: 10.1016/j.scr.2017.11.003. Epub 2017 Nov 7.

Abstract

The class Ia anti-arrhythmic drug ajmaline is used clinically to unmask latent type I ECG in Brugada syndrome (BrS) patients, although its mode of action is poorly characterised. Our aims were to identify ajmaline's mode of action in human induced pluripotent stem cell (hiPSC)-derived cardiomyocytes (CMs), and establish a simple BrS hiPSC platform to test whether differences in ajmaline response could be determined between BrS patients and controls. Control hiPSCs were differentiated into spontaneously contracting cardiac clusters. It was found using multi electrode array (MEA) that ajmaline treatment significantly lengthened cluster activation-recovery interval. Patch clamping of single CMs isolated from clusters revealed that ajmaline can block both INa and IKr. Following generation of hiPSC lines from BrS patients (absent of pathogenic SCN5A sodium channel mutations), analysis of hiPSC-CMs from patients and controls revealed that differentiation and action potential parameters were similar. Comparison of cardiac clusters by MEA showed that ajmaline lengthened activation-recovery interval consistently across all lines. We conclude that ajmaline can block both depolarisation and repolarisation of hiPSC-CMs at the cellular level, but that a more refined integrated tissue model may be necessary to elicit differences in its effect between BrS patients and controls.

Keywords: Activation-recovery interval; Ajmaline; Brugada syndrome; I(Kr); I(Na); hiPSC-cardiomyocytes.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Ajmaline / administration & dosage*
  • Anti-Arrhythmia Agents / administration & dosage*
  • Brugada Syndrome / drug therapy*
  • Brugada Syndrome / genetics
  • Brugada Syndrome / metabolism
  • Brugada Syndrome / physiopathology
  • Cell Differentiation / drug effects
  • Heart / drug effects*
  • Heart / physiopathology
  • Humans
  • Male
  • Middle Aged
  • Myocytes, Cardiac / cytology
  • Myocytes, Cardiac / drug effects*
  • Myocytes, Cardiac / metabolism
  • NAV1.5 Voltage-Gated Sodium Channel / genetics
  • NAV1.5 Voltage-Gated Sodium Channel / metabolism
  • Patch-Clamp Techniques
  • Pluripotent Stem Cells / cytology
  • Pluripotent Stem Cells / drug effects*
  • Pluripotent Stem Cells / metabolism

Substances

  • Anti-Arrhythmia Agents
  • NAV1.5 Voltage-Gated Sodium Channel
  • SCN5A protein, human
  • Ajmaline