Nitric oxide involvement in the delayed antiarrhythmic effect of treadmill exercise in dogs

Ágnes Hajnal, Orsolya Nagy, Ágnes Litvai, Julius Papp, James R. Parratt, Ágnes Végh

Research output: Contribution to journalArticle

18 Citations (Scopus)

Abstract

We have shown previously that a single period of treadmill exercise in dogs protects the heart against the severe ventricular arrhythmias that arise when a major (anterior descending) branch of the left coronary artery is occluded following anaesthesia 24 h later. This protection is aminoguanidine sensitive, suggesting a role for nitric oxide (NO) in this exercise-induced delayed antiarrhythmic effect. The present study has further examined the possible role of NO as a mediator and/or as a trigger using the selective induced (iNOS) inhibitor S-(2-aminoethyl)-methyl-isothiourea (AEST) and the specific but not selective nitric oxide synthase inhibitor Nω-nitro-L-arginine- methyl-ester (L-NAME). Exercise markedly reduced the severity of ischaemia and reperfusion-induced ventricular arrhythmias 24 h later. Thus, only one of the dogs (8%) so exercised fibrillated on occlusion (contrast 46% in the control, non-exercised dogs; P < 0.05) and the marked changes in the inhomogeneity of electrical activation that occur in the ischaemic region following occlusion were much reduced (P < 0.05 compared to controls). This delayed exercise-induced cardioprotection was significantly attenuated by the nitric oxide synthase (NOS) inhibitors L-NAME, given prior to the exercise protocol and by AEST given prior to the coronary artery occlusion. For example, survival from the ischaemia-reperfusion insult was 54% in the exercise dogs, 0% in the controls and 14% in those dogs given a NOS inhibitor. We conclude that nitric oxide (NO) is both the trigger and the mediator of this delayed protection against ischaemia and reperfusion-induced arrhythmias.

Original languageEnglish
Pages (from-to)1960-1971
Number of pages12
JournalLife sciences
Volume77
Issue number16
DOIs
Publication statusPublished - Sep 2 2005

Keywords

  • Delayed preconditioning
  • Exercise
  • Ischaemia-reperfusion
  • Nitric oxide
  • Ventricular arrhythmias
  • iNOS

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)
  • Pharmacology, Toxicology and Pharmaceutics(all)

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