| Arterial chemoreceptors, ventilation and heart rate in man. | |
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MedLine Citation:
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PMID: 599415 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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1. Transient changes of heart rate (HR) and ventilation were recorded following step changes in alveolar gas composition in three healthy subjects. From a steady state of normo- or slightly hypercapnic hypoxia (PA,CO2 38-46 torr, PA,O2 50-60 torr) arterial chemoreceptor stimulation was transiently relieved by breathing a CO2-free mixture for two breaths, either pur O2 (causing a fall in PA,CO2 and a rise in PA,O2; O2 test) or a low O2 mixture (causing a fall in PA,CO2 without any change in PA, O2; CO2 test). For both test types ventilation was either allowed to change freely ('free-breathing' tests) or was consciously maintained at the pre-test level by the subjects ('controlled-breathing tests). The circulatory delay from the lungs to the ear was measured with a sensitive ear oximeter. 2. In all 'free-breathing' tests ventilation decreased significantly after a mean latency of 5.2 sec; the average lung-ear circulation time was 4.9 sec. HR increased slightly above pre-test levels in eighty-one of one hundred and four tests of all types, the changes being significant after a latency identical to that of the ventilatory changes. Except in the 'controlled-breathing' CO2 tests this early tachycardia was followed by a decrease in HR within the following 5-6 sec. 3. These findings indicate that the primary effect of withdrawal of arterial chemoreceptor stimulation in conscious man as in the anesthetized animal is tachycardia. The secondary development of bradycardia in 'free-breathing' CO2 tests is probably due to the operation of a lung reflex sensing changes in ventilation. The absence of bradycardia in 'controlled-breathing' CO2 tests and its presence in 'controlled-breathing' O2 tests, finally, suggest that relief of systemic hypoxia causes a slowing of the heart not due to lung reflexes but to some other mechanism which operates with a latency nearly twice as long as the arterial chemoreflex. |
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Authors:
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D B Drysdale; E S Petersen |
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Publication Detail:
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Type: Journal Article |
Journal Detail:
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Title: The Journal of physiology Volume: 273 ISSN: 0022-3751 ISO Abbreviation: J. Physiol. (Lond.) Publication Date: 1977 Dec |
Date Detail:
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Created Date: 1978-03-10 Completed Date: 1978-03-10 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: 109-20 Citation Subset: IM |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Adult Anoxia / physiopathology Arteries / innervation* Carbon Dioxide Chemoreceptor Cells / physiology* Heart Rate* Humans Male Oxygen Respiration* |
| Chemical | |
Reg. No./Substance:
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124-38-9/Carbon Dioxide; 7782-44-7/Oxygen |
| Comments/Corrections | |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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