NOS1 and ventricular fibrillation: Exploration of the physiology of these nNOS neurons requires further study, but there is an important correlation of the present data to our earlier studies performed using isolated innervated rabbit heart preparations, showing the protective effects of cervical vagus nerve stimulation against ventricular fibrillation to be dependent only on nitrergic postganglionic fibers.23, 33, 34 The results shown here are the first to provide anatomical support for the likely involvement of these neurons in the neurocardiac effects.