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Inter-relations among declines in arterial distensibility, baroreflex function and respiratory sinus arrhythmia
Padmini Kaushal1, J Andrew Taylor
1Laboratories for Cardiovascular Research, Hebrew Rehabilitation Center For Aged Research and Training Institute, and Harvard Medical School Division on Aging, Boston, Massachusetts 02131, USA.
Journal of the American College of Cardiology
|May 3, 2002
Summary
Aging reduces arterial baroreflex function due to decreased carotid distensibility, but does not lower resting cardiac vagal tone. This impacts cardiovascular risk factors.
Area of Science:
- Cardiovascular physiology
- Autonomic nervous system function
- Aging research
Background:
- Cardiovascular (CV) risk is linked to reduced carotid distensibility, impaired baroreflex function, and diminished respiratory sinus arrhythmia (RSA).
- These factors may represent a direct connection between structural and neural CV deficits.
Purpose of the Study:
- To investigate the hypothesis that age-related structural deficits, specifically decreased carotid distensibility, blunt the arterial baroreflex.
- To determine if blunted baroreflex function reduces resting cardiac vagal tone.
Main Methods:
- Compared baroreflex function (mechanostructural and neural components) and RSA in young and older adults.
- Subjects were screened for CV and autonomic diseases.
Main Results:
- Older adults had significantly lower RSA, reduced mechanical transduction of pressure to vessel stretch, and markedly lower arterial baroreflex gain.
- Neural transduction of stretch to vagal outflow showed a trend towards reduction.
- Path analysis indicated both mechanical and neural components contribute to baroreflex gain, but lower gain in older adults did not correlate with lower RSA.
Conclusions:
- Decreased carotid distensibility with age impairs arterial baroreflex function.
- This impairment does not result in reduced resting vagal outflow or lower RSA.