Effect of aging on the cardiovascular regulatory systems in healthy women.
Aging, independently from the hormonal status, is a major risk factor for cardiovascular morbidity in healthy women. Therefore, we studied the effect of healthy aging on the cardiovascular homeostatic mechanisms in premenopausal and postmenopausal women with similar estrogen levels. Twelve healthy postmenopausal women, confirmed by follicular-stimulating hormone (FSH) and luteal hormone (LH) levels, were compared with 14 normally menstruating women during the early follicular phase (young-EF), to avoid as much as possible the effects of estrogen. Systolic BP was 108 +/- 1.5 vs. 123 +/- 2.5 (P < 0.001), supine norepinephrine was 260 +/- 30 vs. 216 +/- 45 and upright 640 +/- 100 vs. 395 +/- 50 pg/ml (P = 0.05) in young-EF vs. postmenopausal, respectively. Plasma renin activity and aldosterone remained unchanged. Vagal cardiac tone indices decreased significantly with aging (young-EF vs. postmenopausal): high-frequency (HF) band, root mean square successive differences (rMSSD) and proportion of R-R intervals >50 ms (PNN50%) were 620 +/- 140 vs. 270 +/- 70 (P = 0.04), 53 +/- 7 vs. 30 +/- 3 (P = 0.02), and 23 +/- 5 vs. 10 +/- 3 (P = 0.04), respectively. LF to HF ratio was 0.85 +/- 0.17 in young-EF and became 1.5 +/- 0.22 in postmenopausal (P = 0.03). Both arms of the baroreflex, +BRS (29 +/- 5 vs. 13.5 +/- 2.5, P = 0.01) and -BRS (26 +/- 4 vs. 15 +/- 1.5, P = 0.02) decreased with aging. Cardiovascular alpha(1)-adrenoreceptor responsiveness significantly increased and beta-decreased in postmenopausal compared with young EF (P < 0.001, both). The corrected QT intervals (QTc) were similar, whereas corrected JT intervals (JTc) and JTc to QTc ratio were prolonged in the postmenopausal group. We conclude that in young women, parasympathetic control is the main regulator of the cardiovascular system and in postmenopausal women, sympathetic tone dominates. The transition from parasympathetic to sympathetic control may contribute to the increased cardiovascular morbidity with aging.
Lavi
Shahar
S
J. Recanati Autonomic Dysfunction Center, Medicine A, Rambam Medical Center, Haifa 31096 Israel.
Nevo
Ori
O
Thaler
Israel
I
Rosenfeld
Rimma
R
Dayan
Lior
L
Hirshoren
Nir
N
Gepstein
Lior
L
Jacob
Giris
G
D000328:Adult; D000368:Aged; D000375:Aging / Q000502:physiology*; D017704:Baroreflex / Q000502:physiology; D001794:Blood Pressure / Q000502:physiology; D001827:Body Height / Q000502:physiology; D015992:Body Mass Index; D001835:Body Weight / Q000502:physiology; D002320:Cardiovascular Physiological Phenomena; D004562:Electrocardiography; D005260:Female; D005640:Follicle Stimulating Hormone / Q000097:blood; D005498:Follicular Phase / Q000502:physiology; D006339:Heart Rate / Q000502:physiology; D006728:Hormones / Q000097:blood; D006801:Humans; D007986:Luteinizing Hormone / Q000097:blood; D008598:Menstruation / Q000502:physiology; D008875:Middle Aged; D018377:Neurotransmitter Agents / Q000097:blood; D017698:Postmenopause / Q000502:physiology; D011941:Receptors, Adrenergic / Q000502:physiology
D006728:Hormones; D018377:Neurotransmitter Agents; D011941:Receptors, Adrenergic; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone