OBJECTIVE This study investigated the dominance of each limb of the autonomic nervous system and tested sympathetic-vagal interactions in the human ventricle and atrium after administration of propranolol and atropine. PATIENTS AND METHODS The 90% monophasic action potential duration (MAPD90) and the effective refractory period (ERP) at the right ventricular apex (RV) and the right lateral at...

The role of endogenous nitric oxide (NO) in modulating the excitatory response of distal airways to vagal stimulation is unknown. In decerebrate, ventilated, open-chest piglets aged 3-10 days, lung resistance (RL) was partitioned into tissue resistance (Rti) and airway resistance (Raw) by using alveolar capsules. Changes in RL, Rti, and Raw were evaluated during vagal stimulation at increasing ...

The role of the autonomic nervous system in modulating reperfusion arrhythmias is still unclear. Experiments with sympathetic denervation or alpha- and beta-adrenergic blocking agents have provided mixed results, while the effect of parasympathetic activation has not been investigated extensively. The effect of bilateral vagotomy and of vagal stimulation was studied, with and without attendant ...

BACKGROUND Previous evidence has shown that increased sympathetic tone enhances the cesium chloride (Cs)-induced early afterdepolarizations (EADs) and ventricular tachycardias (VTs). METHODS AND RESULTS We assessed the effects of vagal stimulation on Cs-induced EADs and ventricular arrhythmias in the rabbit heart. Monophasic action potentials (MAPs) of the left ventricular endocardium were re...

Neuropeptide Y (NPY) is stored with norepinephrine in sympathetic nerves throughout the cardiovascular system and is released during activation of the sympathetic nervous system in humans and other animals. After stimulation of the cardiac sympathetic nerves in anesthetized dogs, the action of the vagus nerve on heart rate is attenuated for a prolonged period. This attenuation of cardiac vagal ...

We determined the effects of changing the spatial dispersion of acetylcholine release on the phase-dependent chronotropic responses to vagal stimulation in anesthetized dogs. We stimulated the vagus nerves with one brief burst of electrical pulses each cardiac cycle, and we changed the timing of the stimulus by a small, constant amount each cardiac cycle to scan the entire cycle. To vary the he...

Neuropeptide Y and norepinephrine are localized in sympathetic nerve terminals throughout the heart. We sought to determine the functional distribution of the neuropeptide Y-containing sympathetic fibers to the sinus and atrioventricular (AV) nodal regions. We recorded cycle length, AV interval, and arterial pressure in 14 anesthetized dogs. We assessed the release of neuropeptide Y from sympat...

Patients affected by inborn errors of metabolism can develop catastrophic epilepsies ineligible for resective surgery. Few reports concerning vagal nerve stimulation in patients with epileptic encephalopathy in the context of metabolic diseases have been published in the literature. Drug-resistant epilepsies in metabolic disease could be a specific target for vagal nerve stimulation, although t...

We hypothesized that pituitary adenylate cyclase-activating polypeptide (PACAP) activates intracardiac postganglionic parasympathetic nerves and has a different effect than cervical vagal stimulation. We measured effective refractory period (ERP) and conduction velocity at four atrial sites [high right atrium (HRA), low right atrium (LRA), high left atrium (HLA), and low left atrium (LLA)] and ...