Nadolol block of Nav1.5 does not explain its efficacy in the long QT syndrome

Alessandra Besana, Dao W. Wang, Alfred L. George, Peter J. Schwartz*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

25 Scopus citations

Abstract

Beta-adrenergic receptor antagonists (β-blockers) are the therapy of choice for the long QT syndrome but their efficacy is not homogeneous: propranolol and nadolol are the most effective, whereas metoprolol is associated with more treatment failures. Propranolol has a blocking effect on the sodium current ("membrane-stabilizing" effect), and it has been hypothesized that the efficacy of nadolol might be due to a similar effect. Accordingly, we used whole-cell patch-clamp recording to assess propranolol, nadolol, and metoprolol block of wild-type or mutant cardiac sodium channels (Nav1.5) coexpressed with β1 subunit in tsA201 cells. Nadolol had a ∼20% non-use-dependent blocking effect on peak sodium current and no effect on the persistent current evoked by the LQT3 mutant A1330D, whereas propranolol blocked Nav1.5 in a use-dependent manner and reduced A1330D persistent current. Metoprolol had no effect on either the peak or persistent current. Analysis of the biophysical properties of the channel revealed that both nadolol and propranolol cause hyperpolarizing shifts on voltage dependence of activation and steady-state inactivation, whereas metoprolol shifts only the activation curve. These results provide partial explanation for the differences between nadolol and metoprolol but do not explain the similar clinical efficacy of nadolol and propranolol.

Original languageEnglish (US)
Pages (from-to)249-253
Number of pages5
JournalJournal of Cardiovascular Pharmacology
Volume59
Issue number3
DOIs
StatePublished - Mar 2012

Keywords

  • long QT syndrome
  • nadolol
  • sodium channel blockers
  • β-blockers

ASJC Scopus subject areas

  • Pharmacology
  • Cardiology and Cardiovascular Medicine

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