Ion channels, long QT syndrome and arrhythmogenesis in ageing

Clin Exp Pharmacol Physiol. 2017 Dec;44 Suppl 1(Suppl Suppl 1):38-45. doi: 10.1111/1440-1681.12721. Epub 2017 Sep 20.

Abstract

Ageing is associated with increased prevalences of both atrial and ventricular arrhythmias, reflecting disruption of the normal sequence of ion channel activation and inactivation generating the propagated cardiac action potential. Experimental models with specific ion channel genetic modifications have helped clarify the interacting functional roles of ion channels and how their dysregulation contributes to arrhythmogenic processes at the cellular and systems level. They have also investigated interactions between these ion channel abnormalities and age-related processes in producing arrhythmic tendency. Previous reviews have explored the relationships between age and loss-of-function Nav 1.5 mutations in producing arrhythmogenicity. The present review now explores complementary relationships arising from gain-of-function Nav 1.5 mutations associated with long QT3 (LQTS3). LQTS3 patients show increased risks of life-threatening ventricular arrhythmias, particularly after 40 years of age, consistent with such interactions between the ion channel abnormailities and ageing. In turn clinical evidence suggests that ageing is accompanied by structural, particularly fibrotic, as well as electrophysiological change. These abnormalities may result from biochemical changes producing low-grade inflammation resulting from increased production of reactive oxygen species and superoxide. Experimental studies offer further insights into the underlying mechanisms underlying these phenotypes. Thus, studies in genetically modified murine models for LQTS implicated action potential recovery processes in arrhythmogenesis resulting from functional ion channel abnormalities. In addition, ageing wild type (WT) murine models demonstrated both ion channel alterations and fibrotic changes with ageing. Murine models then suggested evidence for interactions between ageing and ion channel mutations and provided insights into potential arrhythmic mechanisms inviting future exploration.

Keywords: ageing; cardiac arrhythmia; fibrotic change; long QT syndrome; murine models; sodium channel.

Publication types

  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Action Potentials / genetics*
  • Age Factors
  • Aging / genetics*
  • Aging / metabolism
  • Animals
  • Genetic Predisposition to Disease
  • Heart Rate / genetics*
  • Humans
  • Incidence
  • Kinetics
  • Long QT Syndrome / epidemiology
  • Long QT Syndrome / genetics*
  • Long QT Syndrome / metabolism
  • Long QT Syndrome / physiopathology
  • Mutation*
  • NAV1.5 Voltage-Gated Sodium Channel / genetics*
  • NAV1.5 Voltage-Gated Sodium Channel / metabolism
  • Phenotype
  • Risk Factors

Substances

  • NAV1.5 Voltage-Gated Sodium Channel
  • SCN5A protein, human
  • Scn5a protein, mouse

Supplementary concepts

  • Long Qt Syndrome 3