Activity of in vivo canine cardiac plexus neurons

Abstract

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 cardiac cycle in 39% and with the respiratory cycle in 8% of the identified neurons. Neuronal activity occurred in specific phases of the cardiac cycle when arterial pressure was between approximately 70 and 175 mmHg. During increases in systolic pressure induced by positive inotropic agents or aortic occlusion, responses of neurons that displayed cardiovascular-related activity were enhanced. These responses persisted after acute decentralization. The activity of 14% of all identified neurons was altered when discrete regions of the heart, great thoracic vessels, or lungs were mechanically distorted by gentle touch. Trains of stimuli, but not single stimuli, delivered to the vagosympathetic complexes, stellate ganglia, or cardiopulmonary nerves activated ganglionic neurons in intact or acutely decentralized preparations. It is concluded that the activity of some cardiac ganglion neurons is related to cardiovascular or respiratory dynamics and that some of these neurons receive inputs from sympathetic and parasympathetic efferent axons as well as from cardiac mechanoreceptors.

Nicotinic mechanisms in the autonomic control of organ systems

“…Originally the intracardiac ganglia were depicted as relay stations where preganglionic and postganglionic parasympathetic neurons synapse (Blomquist et al, 1987). In the past decade it has become evident that these intracardiac ganglionated plexuses contain both cholinergic and adrenergic neurons, as well as interneurons and sensory afferents (Ardell and Randall, 1986;Blomquist et al, 1987;Moravec and Moravec, 1987;Ardell et al, 1988;Gagliardi et al, 1988;Armour and Hopkins, 1990). After removal of all their extracardiac neuronal inputs intracardiac neurons retain their ability for synaptic interactions suggesting that local reflexes may control cardiac dynamics independent of the CNS (Murphy et al, 1994;Armour et al, 1998;Thompson et al, 2000).…”

Neuromodulation targets intrinsic cardiac neurons to attenuate neuronally mediated atrial arrhythmias

“…Activity generated by neurons in the RAGP was recorded in situ, as reported previously (3,14). Briefly, to decrease epicardial motion during each cardiac cycle, a circular ring of stiff wire was placed gently on the epicardial fat on the ventral surface of the right atrium-a region known to contain the RAGP.…”

“…The activity generated by individual neuronal somata was identified by the amplitude and configuration (waveform recognition) of these recorded action potentials, using the Spike 2 program. By using these techniques and criteria, action potentials generated by individual somata and/or dendrites, rather than axons of passage, can be recorded for extended periods of time (3,4,14).…”

The Autonomic Nervous System and Atrial Fibrillation: The Roles of Pulmonary Vein Isolation and Ganglionated Plexi Ablation

“…Preliminary evidence from basic studies 70,71 indicate that the extrinsic autonomic input to the heart, i.e., from the brain and spinal cord, exerts an inhibitory control over the ICANS suggesting www.jafib.comlong term (1 year follow-up) freedom from AF recurrence in 94%. Also, others have reported that drugs that were ineffective prior to GP ablation could be used to maintain sinus rhythm in patients still inducible after GP ablation and PVI .…”