Peripheral Chemoreflex and Baroreflex Interactions in Cardiovascular Regulation in Humans
We tested the hypothesis that activation of peripheral chemoreceptors with acute isocapnic hypoxia resets arterial baroreflex control of both heart rate and sympathetic vasoconstrictor outflow to higher pressures, resulting in increased heart rate and muscle sympathetic nerve activity without change...
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Published in | The Journal of physiology Vol. 552; no. 1; pp. 295 - 302 |
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Main Authors | , , |
Format | Journal Article |
Language | English |
Published |
Oxford, UK
The Physiological Society
01.10.2003
Blackwell Publishing Ltd Blackwell Science Inc |
Subjects | |
Online Access | Get full text |
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Summary: | We tested the hypothesis that activation of peripheral chemoreceptors with acute isocapnic hypoxia resets arterial baroreflex
control of both heart rate and sympathetic vasoconstrictor outflow to higher pressures, resulting in increased heart rate
and muscle sympathetic nerve activity without changes in baroreflex sensitivity. We further hypothesized that this resetting
would not occur during isocapnic hyperpnoea at the same breathing rate and depth as during isocapnic hypoxia. In 12 healthy,
non-smoking, normotensive subjects (6 women, 6 men, 19-36 years), we assessed baroreflex control of heart rate and muscle
sympathetic nerve activity using the modified Oxford technique during normoxia, isocapnic hyperpnoea, and isocapnic hypoxia
(85 % arterial O 2 saturation). While isocapnic hyperpnoea did not alter heart rate, arterial pressure, or sympathetic outflow, hypoxia increased
heart rate from 61.9 ± 1.8 to 74.7 ± 2.7 beats min â1 ( P < 0.05), increased mean arterial pressure from 97.4 ± 2.0 to 103.9 ± 3.3 mmHg ( P < 0.05), and increased sympathetic activity 22 ± 13 % relative to normoxia and 72 ± 21 % ( P < 0.05) relative to hyperpnoea alone. The sensitivity for baroreflex control of both heart rate and sympathetic activity
was not altered by either hypoxia or hyperpnoea. Thus, it appears that acute activation of peripheral chemoreceptors with
isocapnic hypoxia resets baroreflex control of both heart rate and sympathetic activity to higher pressures without changes
in baroreflex sensitivity. Furthermore, these effects appear largely independent of breathing rate and tidal volume. |
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Bibliography: | ObjectType-Article-2 SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 23 ObjectType-Article-1 ObjectType-Feature-2 |
ISSN: | 0022-3751 1469-7793 |
DOI: | 10.1113/jphysiol.2003.050708 |