Age- and gender-related changes in endothelin and catecholamine release, and in autonomic balance in response to head-up tilt.
1. There is an increase in circulating levels of vasoconstrictive hormones and an alteration in baroreceptor responsiveness with aging. The role of changes in endothelium-dependent and -independent vasoconstrictive hormones in relation to age and gender, with simultaneous assessment of autonomic balance in response to head-up tilt, has been incompletely studied. 2. Sixteen young [25 +/- 3 years (mean +/- SEM)] and 16 older normal volunteers (68 +/- 7 years) underwent a 30 min head-up tilt test at 60 degrees. Haemodynamics were measured every 5 min and blood samples for neurohormone measurement were drawn at baseline, 5, 10, 15 and 30 min into the test. Heart rate variability was analysed in 5 min segments at the baseline, and during the test. The younger subjects exhibited a greater increase in heart rate and diastolic blood pressure, despite lower absolute levels of noradrenaline (norepinephrine) and endothelin-1. Analysis of heart rate variability yielded a decrease in both high- and low-frequency bands in the aged; power at low-frequency decreased only in the young subjects. The age-related differences in blood pressure and noradrenaline levels were markedly attenuated in the female subjects. In addition, endothelin-1 levels and power spectral measurements at low frequency were the lowest in younger females throughout the tilt. 3. Despite attenuated cardiovascular response to tilt, both systemic adrenergic 'drive' and endothelin-1 levels increase in parallel with aging. Thus, endothelium-dependent and -independent vasoconstrictive hormone levels increase with age in the resting state and in response to neurohumoral stimulation in humans.
White
M
M
Department of Medicine, Montreal Heart Institute, Quebec, Canada.
Courtemanche
M
M
Stewart
D J
DJ
Talajic
M
M
Mikes
E
E
Cernacek
P
P
Vantrimpont
P
P
Leclerc
D
D
Bussières
L
L
Rouleau
J L
JL
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D001341:Autonomic Nervous System / Q000502:physiology*; D001794:Blood Pressure / Q000502:physiology; D002395:Catecholamines / Q000097:blood / Q000378:metabolism*; D019332:Endothelin-1 / Q000097:blood / Q000378:metabolism*; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008297:Male; D011187:Posture / Q000502:physiology*; D012737:Sex Factors; D012815:Signal Processing, Computer-Assisted; D018709:Statistics, Nonparametric; D018667:Tilt-Table Test
D002395:Catecholamines; D019332:Endothelin-1