Impairment of Autonomic Function Induced by Posture Change in Postmenopausal Women

Abstract

This study was designed to determine if there is a difference in autonomic regulation induced by posture change between postmenopausal and young women. To evaluate autonomic nervous system function, spectral analysis of heart rate variability (HRV) was done in postmenopausal women (n = 13, 46-59 years of age), age-matched men (n = 8, 45-55 years of age), and young women (n = 10, 20-37 years of age) for 3-min periods of controlled frequency breathing (15 breaths/min) in supine followed by sitting positions. In the supine position, the R-R interval variation in older persons decreased significantly compared with that during the follicular phase in young women. Furthermore, the high-frequency (HF) components of HRV, which reflect only parasympathetic activity, were lower in older subjects than in young women. Following a change of position from supine to sitting, the HF component did not change significantly in the postmenopausal women or the men, but the low/high frequency (LF/HF) component ratio, which reflects the balance of autonomic nerve activities, increased significantly in the men. These results suggest that cardiac parasympathetic tone may be reduced in older persons in comparison with young women. Furthermore, arterial baroreflex control of parasympathetic nerve activity caused by posture changes is impaired in the postmenopausal women and aged-matched men. The baroreflex control of the sympathetic component is maintained in the men but not in the postmenopausal women. These differences might result in part from changes in the level of female hormones.

Effect of a health education program on climacteric women

“…One report about the features of the ANS function of climacteric women states that parasympathetic nerve activity decreases even during the regular menstrual cycle and the parasympathetic nerve reflex function also decreases when the woman changes body position 22 . In addition, ANS reflex function decreases in both parasympathetic and sympathetic nerves when the menstrual cycles of perimenopausal climacteric women are irregular 23 . The ANS activity tends to gradually decrease with age and the rate of the decline in parasympathetic nerve activity (HF) increases after the age of 40 years 24 .…”

Study of comparison between autonomic dysfunction and dyslipidemia in healthy postmenopausal women

“…Their results suggested that cardiac parasympathetic tone may be reduced in older persons in comparison with young women. [ 14 ]…”

Study of Comparison Between Autonomic Dysfunction and Dyslipidemia in Healthy Postmenopausal Women.

“…Their results suggested that cardiac parasympathetic tone may be reduced in older persons in comparison with young women. [14] In the Framingham Heart Study, [15] plasma TGL is an independent predictor of coronary artery disease. This study presented with TGL level >140 mg/dl in postmenopausal age group in 35% of cases.…”