| Human autonomic rhythms: vagal cardiac mechanisms in tetraplegic subjects. | |
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MedLine Citation:
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PMID: 8014908 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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1. We studied eight young men (age range: 20-37 years) with chronic, clinically complete high cervical spinal cord injuries and ten age-matched healthy men to determine how interruption of connections between the central nervous system and spinal sympathetic motoneurones affects autonomic cardiovascular control. 2. Baseline diastolic pressures and R-R intervals (heart periods) were similar in the two groups. Slopes of R-R interval responses to brief neck pressure changes were significantly lower in tetraplegic than in healthy subjects, but slopes of R-R interval responses to steady-state arterial pressure reductions and increases were comparable. Plasma noradrenaline levels did not change significantly during steady-state arterial pressure reductions in tetraplegic patients, but rose sharply in healthy subjects. The range of arterial pressure and R-R interval responses to vasoactive drugs (nitroprusside and phenylephrine) was significantly greater in tetraplegic than healthy subjects. 3. Resting R-R interval spectral power at respiratory and low frequencies was similar in the two groups. During infusions of vasoactive drugs, low-frequency R-R interval spectral power was directly proportional to arterial pressure in tetraplegic patients, but was unrelated to arterial pressure in healthy subjects. Vagolytic doses of atropine nearly abolished both low- and respiratory-frequency R-R interval spectral power in both groups. 4. Our conclusions are as follows. First, since tetraplegic patients have significant levels of low-frequency arterial pressure and R-R interval spectral power, human Mayer arterial pressure waves may result from mechanisms that do not involve stimulation of spinal sympathetic motoneurones by brainstem neurones. Second, since in tetraplegic patients, low-frequency R-R interval spectral power is proportional to arterial pressure, it is likely to be mediated by a baroreflex mechanism. Third, since low-frequency R-R interval rhythms were nearly abolished by atropine in both tetraplegic and healthy subjects, these rhythms reflect in an important way rhythmic firing of vagal cardiac motoneurones. |
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Authors:
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J Koh; T E Brown; L A Beightol; C Y Ha; D L Eckberg |
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Publication Detail:
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Type: Journal Article; Research Support, U.S. Gov't, Non-P.H.S.; Research Support, U.S. Gov't, P.H.S. |
Journal Detail:
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Title: The Journal of physiology Volume: 474 ISSN: 0022-3751 ISO Abbreviation: J. Physiol. (Lond.) Publication Date: 1994 Feb |
Date Detail:
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Created Date: 1994-07-22 Completed Date: 1994-07-22 Revised Date: 2009-11-18 |
Medline Journal Info:
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Nlm Unique ID: 0266262 Medline TA: J Physiol Country: ENGLAND |
Other Details:
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Languages: eng Pagination: 483-95 Citation Subset: IM; S |
Affiliation:
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Department of Medicine, Hunter Holmes McGuire Department of Veterans Affairs Medical Center, Richmond, VA. |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Adult Atropine / pharmacology Autonomic Nervous System / physiopathology* Blood Pressure Carotid Arteries / innervation, physiology Catecholamines / blood Heart / drug effects, innervation, physiology*, physiopathology Humans Male Motor Neurons / physiology Nitroprusside / pharmacology Phenylephrine / pharmacology Pressoreceptors / physiology Quadriplegia / physiopathology* Spinal Cord Injuries / physiopathology Vagus Nerve / physiology |
| Grant Support | |
ID/Acronym/Agency:
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HL22296/HL/NHLBI NIH HHS |
| Chemical | |
Reg. No./Substance:
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0/Catecholamines; 15078-28-1/Nitroprusside; 51-55-8/Atropine; 59-42-7/Phenylephrine |
| Investigator | |
Investigator/Affiliation:
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D L Eckberg / Med Coll VA, Richmond |
| Comments/Corrections | |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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