NOS1 and cardiac arrhythmia: Since increased oxidative stress and diastolic dysfunction are often associated with structural and functional pathology of the myocardium, such as hypertrophy, arrhythmias and heart failure, nNOS modulation of various cardiac oxidases or improving diastolic function of the myocardium under pressure-overload enable nNOS to protect the heart from structural and functional remodeling those underlie fatal heart failure.