Referenced in: none

Automatically associated channels: Kir2.3

Title: Neuronal nitric oxide synthase protects against myocardial infarction-induced ventricular arrhythmia and mortality in mice.

Authors: Dylan E Burger, Xiangru Lu, Ming Lei, Fu-Li Xiang, Lamis Hammoud, Mao Jiang, Hao Wang, Douglas L Jones, Stephen M Sims, Qingping Feng

Journal, date & volume: Circulation, 2009 Oct 6 , 120, 1345-54

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/19770398

Abstract
Neuronal nitric oxide synthase (nNOS) is expressed in cardiomyocytes and plays a role in regulating cardiac function and Ca2+ homeostasis. However, the role of nNOS in cardiac electrophysiology after myocardial infarction (MI) is unclear. We hypothesized that nNOS deficiency increases ventricular arrhythmia and mortality after MI.MI was induced in wild-type (WT) or nNOS(-/-) mice by ligation of the left coronary artery. Thirty-day mortality was significantly higher in nNOS(-/-) compared with WT mice. Additionally, nNOS(-/-) mice had impaired cardiac function 2 days after MI. Telemetric ECG monitoring showed that compared with WT, nNOS(-/-) mice had significantly more ventricular arrhythmias and were more likely to develop ventricular fibrillation after MI. Treatment with the L-type Ca2+ channel blocker verapamil reduced the incidence of arrhythmia and ventricular fibrillation in nNOS(-/-) mice after MI. To assess the role of nNOS in Ca2+ handling, patch-clamp and Ca2+ fluorescence techniques were used. Ca2+ transients and L-type Ca2+ currents were higher in nNOS(-/-) compared with WT cardiomyocytes. Additionally, nNOS(-/-) cardiomyocytes exhibited significantly higher systolic and diastolic Ca2+ over a range of pacing frequencies. Treatment with the NO donor S-nitroso N-acetyl-penicillamine decreased Ca2+ transients and L-type Ca2+ current in both nNOS(-/-) and WT cardiomyocytes. Furthermore, S-nitrosylation of Ca2+ handling proteins was significantly decreased in nNOS(-/-) myocardium after MI.Deficiency in nNOS increases ventricular arrhythmia and mortality after MI in mice. The antiarrhythmic effect of nNOS involves inhibition of L-type Ca2+ channel activity and regulation of Ca2+ handling proteins via S-nitrosylation.