Age and autonomic effects on interrelationships between lung volume
and heart rate.
Stanley, Garrett, Davide Verotta, Noah Craft, Ronald A. Siegel, and
Janice B. Schwartz.
University of California, San Francisco, CA, University of
California, Berkeley, Department of Mechanical Engineering,
Department of Pharmacy, Department of Medicine, Cardiovascular
Research Institute, Department of Epidemiology and Biostatistics
APStracts 2:0477H, 1995.
To determine effects of aging and autonomic input on
interrelationships between respiratory and heart rate variability, we
collected 5 minutes lung volume and R-R interval data from 7 young
(27 +/- 3 yr, mean +/- S.D.) and 10 old (69 +/- 6 yr) healthy supine
humans before and after double pharmacological autonomic blockade
(0.2 mg/kg i.v. propranolol, 0.04 mg/kg i.v. atropine). Estimates of
respiratory and heart rate power spectra and linear transfer
functions between the two were generated by Fourier analysis. Age,
double blockade effects, and age-drug interactions were determined by
ANOVA for repeated measures. Basal R-R intervals were unaffected by
age. Double blockade decreased R-R intervals and variability in both
age groups (p<0.0001), but R-R intervals decreased less in old
compared to young (p<0.0001). In contrast, basal respiratory
intervals and S.D. were greater in older subjects (p=0.05) and were
unaffected by double blockade in young and old. Lung volume to heart
rate spectral coherence was highest at frequencies associated with
respiration and greater in young vs. old (p<0.07). Double
blockade decreased lung volume to heart rate variability transfer
function magnitude (p<0.007) and increased phase angle
(p<0.02) without age effects or age-drug interactions.
Conclusions: Heart rate, respiration, and respiration-heart rate
interrelations are altered by aging; and, double autonomic
pharmacological blockade does not eliminate all age-related
differences.
Received 22 June 1995; accepted in final form 11 October 1995.
APS Manuscript Number H573-5.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 6 November 95