Parasympathetic postganglionic pathways to the sinoatrial node
| Autor: | M. J. Duff, Walter C. Randall, M. F. O'Toole, K. M. Bluemel, R. D. Wurster |
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| Rok vydání: | 1990 |
| Předmět: |
Male
Physiology Refractory period Ganglionic Blockers Neural Conduction Hexamethonium Compounds Hexamethonium Pulmonary vein chemistry.chemical_compound Dogs Heart Rate Physiology (medical) Neural Pathways medicine Carnivora Animals Atrium (heart) Sinoatrial Node Sinoatrial node business.industry Ganglia Parasympathetic Neural Inhibition Vagus Nerve Anatomy medicine.disease Electric Stimulation Electrophysiology medicine.anatomical_structure chemistry Pulmonary Veins Peripheral nervous system Injections Intravenous Atrioventricular Node Female Cardiology and Cardiovascular Medicine business Atrioventricular block |
| Zdroj: | American Journal of Physiology-Heart and Circulatory Physiology. 259:H1504-H1510 |
| ISSN: | 1522-1539 0363-6135 |
| Popis: | Vagal ganglia that innervate the canine sinoatrial node (SAN) have been localized to a fat pad overlying and surrounding the right pulmonary vein complex (PVFP). The ventral epicardial surface of the right atrium was mapped in seven dogs anesthetized with alpha-chloralose after beta-blockade (timolol) and cardiac sympathetic and parasympathetic decentralization. A small, concentric bipolar exploring electrode was used to stimulate (during the atrial refractory period and using trains of five to eight stimuli per beat) systematically in the epicardial regions between the PVFP and the SAN. Changes in SAN rate with stimulation were measured, and the anatomic location was identified on a 150-point grid fitted to conform to size and shape of the atrium. Mapping was performed before and after local (PVFP) and systemic ganglionic blockade (hexamethonium). Data reveal that the primary vagal postganglionic pathways to the sinoatrial nodal region are subepicardial and adjacent to the SAN artery along the sulcus terminalis. Hexamethonium in the PVFP abolishes SAN inhibition during preganglionic vagal excitation, without interrupting vagal suppression of atrioventricular conduction. However, SAN slowing (with varying attenuation) continued to occur after hexamethonium (either PVFP or systemically) when the exploring electrode was applied directly over intramural postganglionic fibers between PVFP and sinus node. Attention is directed to existence of a very few synapses closer to SAN, probably in isolated ganglia immersed in fatty connective tissues along the sulcus terminalis. |
| Databáze: | OpenAIRE |
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