Walter C. Randall

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The purpose of this study was to quantify the relative roles of the canine cardiac parasympathetic and sympathetic nerves in controlling the distribution of power within the heart rate (HR) power spectrum using a highly selective surgical technique to parasympathectomize the SA node. DAta were recorded in awake dogs (n = 6) before and after the selective(More)
The activity of 394 spontaneously active neurons located in the ganglionated plexus of the ventral epicardial fat pad overlying the right atrium and pulmonary veins was recorded. Ganglia that contained various numbers of neurons, many with two or more nucleoli, were identified adjacent to the recording sites. Spontaneous activity was correlated with the(More)
Nicotinic and muscarinic mediated synaptic mechanisms were investigated in isolated, canine intracardiac ganglia taken from the right atrial fat pad. Using conventional intracellular microelectrode recording techniques on 216 neurons, fast and slow synaptic potentials were evoked by single or trains of stimulation of presynaptic fibers in interganglionic(More)
Both anatomical and physiologic evidence for relatively rich autonomic innervation of sinoatrial (SAN) and atrioventricular (AVN) regions of the canine heart exist, with indication that SAN is especially responsive to parasympathetic, while AVN is preferentially sensitive to sympathetic regulation. The distribution of autonomic pathways are sufficiently(More)
Direct electrical excitation of small cardiac branches from the thoracic vagus elicited highly localized and differential responses from individualized segments of the myocardium. For example, small nerves from the vagus at the level of the superior pulmonary veins frequently induced moderate inhibition in contractile force of the ipsilateral atrium with(More)
The thoracic cardiac nerves were stimulated in each of 21 dogs anesthetized with alpha chloralose. Recordings were made of heart rate, blood pressure, and contractile force from all four cardiac chambers. Walton-Brodie strain-gauge arches were sutured to both atria, and to three locations of each ventricle, representing both anterior and posterior surfaces.(More)
To gain insight into the mechanisms of reperfusion arrhythmias, we studied ventricular automaticity and conduction characteristics in 35 dogs during 10 minutes of left anterior descending coronary artery (LAD) occlusion and subsequent reperfusion. The frequency of ectopic activity reached a maximum within the first 6-8 minutes after LAD occlusion and then(More)