Postnatal development of peptidergic innervation of the canine heart.

The autonomic innervation of the canine heart develops with considerable regional asymmetry during the early neonatal period. To examine the development of the peptidergic component of the innervation, 28 mongrel puppies 1-6 weeks of age from five litters were studied at weekly intervals. Four of the mothers were also studied as adult and breed controls.

Coronary venous hypertension prevents the formation of the electrophysiological arrhythmogenic substrate of acute ischemia in the dog: salutary effects of preserved myocardial hydration.

Coronary venous hypertension induced by partial coronary sinus obstruction (CSO) in the dog, prevents or delays the predictable ventricular fibrillation (VF) of the early phase of acute ischemia. Also, CSO acting presumably through enhanced myocardial hydration, normalizes the inhomogenous extracellular potassium ([K+]o) accumulation, a major factor in producing the electrophysiological disparities, characteristic of arrhythmogenic substrate. To further clarify the mechanism of early ischemic VF prevention in dogs, radioactive microspheres were used to evaluate regional perfusion changes, resulting from CSO sufficient to raise the coronary sinus pressure to 40 mmHg, before and during ischemia induced by double coronary artery occlusion (CAO) (n=5).

Ventricular fibrillation in the neonate: elusive or illusive?

Ventricular fibrillation (VF) in mature large mammals is usually a terminal event. It constitutes the most common mode of exitus and the main cause of sudden cardiac death in humans. In neonates, VF is of particular interest because it often reverse spontaneously and promptly to potentially become a non-lethal event.

Myocardial electrophysiological effects of neuropeptide Y in dogs.

Neuropeptide Y (NPY) exerts coronary vasomotor and inotropic effects on the canine heart. To test whether NPY also exerts regional myocardial electrophysiological effects, dose-response and time course changes resulting from intravenous and regional intracoronary infusions of NPY were obtained in 14 alpha-chloralose-anesthetized dogs. Under constant ventricular pacing, activation (A), recovery (R), and A-R interval (ARI) maps were constructed from multiplexed unipolar surface electrograms recorded simultaneously from 64 sites within a 1.

Prevention of extracellular K+ inhomogeneity across the ischemic border by coronary venous obstruction in the dog: salutary antiarrhythmic effects of enhanced myocardial hydration.

Partial coronary sinus obstruction (CSO) in the dog prevents or delays the predictable ventricular fibrillation (VF) of the early phase of acute ischemia, by normalizing regional electrophysiological disparities which presumably reflect inhomogeneous extracellular potassium ([K+]o) accumulation. To clarify whether CSO indeed affects [K+]o inhomogeneity, we determined in 12 chloralose anesthetized dogs the dynamic [K+]o changes occurring early during reversible coronary artery occlusion (CAO) involving the mid-left anterior descending branch. These changes were compared to those observed during CAO preceded by CSO sufficient to increase the coronary sinus pressure to 40 mmHg.