Impaired forearm blood flow and vasodilator reserve in healthy postmenopausal women

Combined effect of physical exercise and hormone replacement therapy on cardiovascular and metabolic health in postmenopausal women: A systematic review and meta-analysis

The cardioprotective effect of postmenopausal hormone replacement therapy (HRT) has been demonstrated in several studies. Similarly, physical exercise has yielded positive results. However, the effects of their combination remain inconclusive. This review describes the combined effects of physical exercise and hormone therapy on cardiovascular and metabolic health in postmenopausal women. We searched the Scopus, Web of Science, PubMed, and Embase databases and included randomized controlled trials published up to December 2021 on the combined effects of physical exercise and hormone therapy on cardiovascular and metabolic health in postmenopausal women. We identified 148 articles, of which only seven met the inclusion criteria (386 participants; 91 [23%] HRT + exercise; 104 [27%] HRT; 103 [27%] exercise; 88 [23%] placebo). The combined treatment further decreased systolic blood pressure (SBP) compared to the isolated effect of aerobic training (AT) (mean difference [MD]=-1.69; 95% confidence interval [CI]=-2.65 to -0.72, n=73). Nevertheless, it attenuated the decrease in diastolic blood pressure (DBP) (MD=0.78; 95%CI: 0.22-1.35, n=73), and the increase in peak oxygen consumption (VO2 peak) promoted by exercise (AT + HRT=2.8±1.4 vs AT + placebo=5.8±3.4, P=0.02). The combination of AT and oral HRT improved SBP. However, AT alone seemed to have a better effect on physical fitness and DBP in postmenopausal women.

Mildly elevated diastolic blood pressure increases subsequent risk of breast cancer in postmenopausal women in the Health Examinees-Gem study

Epidemiological evidence suggests that hypertension is associated with breast cancer risk. However, previous studies disregard blood pressure components in the healthy population. We aimed to examine the relationship between systolic and diastolic blood pressure and breast cancer risk in a Korean population-based prospective cohort. A total of 73,031 women from the Health Examinees Gem Study were followed from baseline (2004 to 2013) through 2018. Systolic and diastolic blood pressure were measured by trainee physicians at baseline recruitment and then categorized based on the international guidelines for clinical hypertension. Associations between systolic and diastolic blood pressure with overall breast cancer and stratified by premenopausal and postmenopausal status were evaluated using adjusted multivariable Cox proportional hazard regression. A total of 858 breast cancer cases were recorded for a median follow-up period of 9 years. Compared with the normal DBP category (< 85 mmHg), the normal-high category was positively associated with breast cancer risk in postmenopausal women (85–89 mmHg, HR 1.73 95% CI 1.28–2.33), but not in premenopausal women (85–89 mmHg, HR 0.87 95% CI 0.56–1.35). Similar results were found when all cases of self-reported hypertension were excluded. Results for SBP did not show a significant association with breast cancer risk. The association between DBP and breast cancer suggests DBP could be an important factor in cancer prevention, especially for women after menopause. Our study provides a first detailed approach to understanding the importance of diastolic blood pressure for breast cancer prevention and warrants further investigation.

Impact of premature natural menopause on body composition and physical function in elderly women: A Korean frailty and aging cohort study

Induced premature menopause accelerates the rate of body composition changes (decrease in skeletal muscle mass and increase in fat mass) and deteriorating physical function. However, few studies have focused on the impact of premature natural menopause. This study aimed to investigate the impact of age at natural menopause (ANM) on body composition and physical function in elderly women.Using data from the Korean Frailty and Aging Cohort Study, 765 community-dwelling elderly women aged 70 to 85 years who experienced natural menopause were recruited in this study. Body composition was measured using dual-energy X-ray absorptiometry. Physical function was evaluated by grip strength, the timed up and go test (TUG), and the short physical performance battery (SPPB). Participants were categorized into 4 groups according to their ANM: <40 (premature natural menopause, PNM), 40 to 44 (early natural menopause, ENM), 45 to 54 (normal menopause, NM), and ≥55 (late menopause, LM) years.There were no significant differences in the body composition parameters, such as the appendicular skeletal muscle mass index (PNM: 5.90 ± 0.90 vs ENM: 5.91 ± 0.70 vs NM: 5.85 ± 0.73 vs LM: 5.90 ± 0.75, kg/m2, P = .75) and trunk fat mass index (PNM: 19.4 ± 3.9 vs ENM: 19.9 ± 4.4 vs NM: 19.9 ± 3.9 vs LM: 20.0 ± 3.8, %, P = .87) between the groups. In the physical function evaluation, there was no significant difference between the groups in grip strength (PNM: 19.8 ± 0.6 vs ENM: 20.3 ± 0.4 vs NM: 20.6 ± 0.2 vs LM: 20.6 ± 0.4, kg, P = .53). However, in the TUG (PNM: 11.8 ± 0.4 vs ENM: 10.3 ± 0.3 vs NM: 10.6 ± 0.1 vs LM: 10.2 ± 0.3, seconds, P < .01) and SPPB (PNM: 10.0 ± 0.2 vs ENM: 10.5 ± 0.2 vs NM: 10.6 ± 0.1 vs LM: 10.8 ± 0.2, points, P < .05), the PNM group showed significantly lower values than the other groups did. There was no difference in physical function between the groups except the PNM.Premature natural menopause did not affect the body composition in elderly women but was associated with physical function deterioration. Therefore, more attention should be paid to the prevention of the physical function deterioration caused by premature natural menopause in elderly women.

Beetroot juice intake with different amounts of nitrate does not change aerobic exercise-mediated responses in heart rate variability in hypertensive postmenopausal women: A randomized, crossover and double-blind study

Objectives

To compare the acute effects of a single dose of beetroot juice (BJ) with different concentrations of nitrate (NO₃⁻) on heart rate variability (HRV) in postmenopausal hypertensive women.

Methods

Thirteen hypertensive postmenopausal women (58.1 ± 4.6 years of age and 27 ± 4 kg/m² of BMI) completed the protocol that consisted of three visits with different beverage intakes in a randomized and crossover design. The three beverages were BJ with a high content of nitrate (high-NO₃^-), BJ with a low content of nitrate (low-NO₃^-), and an orange flavored non-caloric drink (OFD). Heart rate (HR) were evaluated during 20 min after sitting rest at 7:20 a.m. (baseline), after they drank one of the drinks, and remained at sitting rest for 120 min and then performed 40 min of aerobic exercise at 65–70% of the HR reserve on a treadmill. HR was recorded for 90 min after exercise for time, frequency, and non-linear domains of HRV index analysis.

Results

Two-way ANOVA showed that there were no interaction effects (time∗sessions) in any of the HRV indexes after exercise in all three sessions. HRV indexes increased after exercise (p = <0.05) similarly in all three sessions when compared with the baseline time point.

Conclusion

Therefore, a single dose of BJ, independent of NO₃⁻ content, does not change aerobic exercise-mediated responses in HRV indexes in hypertensive postmenopausal women.

Isoflavone does not promote additional effects on heart rate variability of postmenopausal women performing combined exercise training: a clinical, controlled, randomized, double-blind study

The aim of the study was to investigate the effects of ingesting isoflavones associated with combined aerobic and resistance exercise training on heart rate variability (HRV) indices in postmenopausal women. Twenty-eight healthy postmenopausal women performed 10 weeks of combined exercise training associated with isoflavone (n = 16) or placebo (n = 12) supplementation. The RR intervals (RRi) were collected for 20 min using a heart rate monitor. Analysis of HRV was performed in time (mean squared difference of successive RRi (RMSSD), standard deviation of all normal RRi (SDNN), and percentage of adjacent RRi differing by more than 50 ms (pNN50)), frequency (low-frequency percentage (LF%), high-frequency percentage (HF%), and low-/high-frequency ratio (LF/HF)), and nonlinear domains (standard deviation of the instantaneous variability of the beat-to-beat interval (SD1), long-term variability of the continuous RRi (SD2), and their ratio (SD2/SD1)). Student's t test did not show differences between groups in any general baseline characteristic variables. The results of the generalized estimating equation tests did not demonstrate interaction or group effects for any HRV indices. However, the results reported time effects for mean RR (p < 0.001), RMSSD (p = 0.044), and SD1 (p = 0.044), with increases in these indices in response to exercise training. There were no time effects for LF%, HF%, LF/HF, SDNN, pNN50, SD2, or SD2/SD1. In conclusion, isoflavone supplementation did not promote additional effects on HRV indices of postmenopausal women subjected to 10 weeks of combined exercise training. Novelty Combined training improves heart rate variability in postmenopausal women. Isoflavone supplementation did not promote additional effects on heart rate variability in postmenopausal women.

Associations Between Heart Rate Recovery Dynamics With Estradiol Levels in 20 to 60 Year-Old Sedentary Women

It is hypothesized that estradiol levels, as well as aging, influence cardiac autonomic function in women. The main aim of this study was to test the correlations between heart rate recovery (HRR) dynamics, as a proxy of cardiac autonomic function, with estradiol levels and age in women. This cross-sectional study involved 44 healthy women. Heart rate (HR) data were obtained beat-by-beat during the entire experiment. Maximal incremental exercise testing (IET) on a cycle ergometer was performed followed by 6 min of recovery. During the IET recovery period, the overall HRR dynamics were evaluated by exponential data modeling (time constant "τ") where shorter τ indicates faster HRR adjustment. Considering the cardiac autonomic complexity, HRR dynamics were also evaluated by delta (Δ) analysis considering different HR data intervals. The relationship between HRR dynamics, estradiol levels and age was tested by Pearson product-moment correlation. The overall HRR dynamics (i.e., τ) were statistically correlated with age (r = 0.58, p < 0.001) and estradiol levels (r = -0.37, p = 0.01). The Δ analysis showed that the slower overall HRR associated with aging was a consequence of slower dynamics occurring within the 45-210 s interval, indicating slower sympathetic withdrawal. In conclusion, aging effects on HRR in women seems to be correlated with a slower sympathetic withdrawal. In addition, the cardioprotective effect previously associated with estradiol seems not to influence the autonomic modulation during exercise recovery periods in women.

Endothelial and inflammatory responses to acute exercise in perimenopausal and late postmenopausal women

Endothelial dysfunction and inflammation are characteristics of subclinical atherosclerosis and may increase through progressive menopausal stages. Evaluating endothelial responses to acute exercise can reveal underlying dysfunction not apparent in resting conditions. The purpose of this study was to investigate markers of endothelial function and inflammation before and after acute exercise in healthy low-active perimenopausal (PERI) and late postmenopausal (POST) women. Flow-mediated dilation (FMD), CD31⁺/CD42b^- and CD62E⁺ endothelial microparticles (EMPs), and the circulating inflammatory factors monocyte chemoattractant protein 1 (MCP-1), interleukin 8 (IL-8), and tumor necrosis factor-α (TNF-α) were measured before and 30 min after acute exercise. Before exercise, FMD was not different between groups (PERI: 6.4 ± 0.9% vs. POST: 6.5 ± 0.8%, P = 0.97); however, after acute exercise PERI tended to improve FMD (8.5 ± 0.9%, P = 0.09), whereas POST did not (6.2 ± 0.8%, P = 0.77). Independent of exercise, we observed transient endothelial dysfunction in POST with repeated FMD measures. There was a group × exercise interaction for CD31⁺/CD42b^- EMPs (P = 0.04), where CD31⁺/CD42b^- EMPs were similar before exercise (PERI: 57.0 ± 6.7 EMPs/μl vs. POST: 58.5 ± 5.3 EMPs/μl, P = 0.86) but were higher in POST following exercise (PERI: 48.2 ± 6.7 EMPs/μl vs. POST: 69.4 ± 5.3 EMPs/μl, P = 0.023). CD62E⁺ EMPs were lower in PERI compared with POST before exercise (P < 0.001) and increased in PERI (P = 0.04) but did not change in POST (P = 0.68) in response to acute exercise. After acute exercise, MCP-1 (P = 0.055), TNF-α (P = 0.02), and IL-8 (P < 0.001) were lower in PERI but only IL-8 decreased in POST (P < 0.001). Overall, these data suggest that perimenopausal and late postmenopausal women display different endothelial and inflammatory responses to acute exercise.

Acute Myocardial Infarction in Women: A Scientific Statement From the American Heart Association

Cardiovascular disease is the leading cause of mortality in American women. Since 1984, the annual cardiovascular disease mortality rate has remained greater for women than men; however, over the last decade, there have been marked reductions in cardiovascular disease mortality in women. The dramatic decline in mortality rates for women is attributed partly to an increase in awareness, a greater focus on women and cardiovascular disease risk, and the increased application of evidence-based treatments for established coronary heart disease. This is the first scientific statement from the American Heart Association on acute myocardial infarction in women. Sex-specific differences exist in the presentation, pathophysiological mechanisms, and outcomes in patients with acute myocardial infarction. This statement provides a comprehensive review of the current evidence of the clinical presentation, pathophysiology, treatment, and outcomes of women with acute myocardial infarction.

Metabolic Syndrome and Menopause: Pathophysiology, Clinical and Diagnostic Significance

Menopause is a risk factor for cardiometabolic diseases, including metabolic syndrome (MetS), type 2 diabetes, and cardiovascular diseases. MetS is a constellation of interdependent factors such as insulin resistance, abdominal obesity, dyslipidemia, and hypertension. The prevalence of MetS in postmenopause is due to loss of the protective role of estrogens and increased circulating androgens resulting in changes to body fat distribution and development of abdominal obesity. Excessive visceral adipose tissue plays an important role due to synthesis and secretion of bioactive substances such as adipocytokines, proinflammatory cytokines, reactive oxygen species, prothrombotic, and vasoconstrictor factors. MetS may also impact risk assessment of breast cancer, osteoporosis and chronic kidney disease, and quality of life during the menopausal transition. Increased MetS has stimulated the exploration of new laboratory tests for early detection and therapies.

Salivary α-amylase and cortisol after exercise in menopause: influence of long-term HRT

OBJECTIVES

This observational prospective study analyzed the effect of an incremental cardiopulmonary exercise test (CPET) on the secretion of salivary biomarkers of the adrenergic nervous system and hypothalamus-pituitary-adrenal (HPA) axis activity by measuring salivary α-amylase and cortisol diurnal trajectories in the setting of long-term hormone replacement therapy (HRT).

METHODS

Fifteen healthy sedentary postmenopausal women who were current HRT users and 15 women who had never used HRT were consecutively recruited. α-Amylase and cortisol were measured in salivary samples collected on the CPET day and on a rest day. Cardiovascular and respiratory fitness parameters were recorded during the CPET challenge.

RESULTS

The participants had very homogeneous somatic characteristics, and they were all in generally good health. The postmenopausal never-HRT users presented an abnormal diurnal pattern of α-amylase at baseline and a flattened response to CPET. In contrast, women on HRT had a physiological α-amylase diurnal pattern and increased salivary α-amylase production during the CPET-induced challenge. The CPET challenge physiologically activated the HPA axis activity, as shown by the increase in the concentration of salivary cortisol during the effort test. HPA axis activity was not affected by long-term HRT. Postmenopausal women using HRT exhibited a cardiorespiratory functional capacity that was significantly (p < 0.05) higher than that of non-users.

CONCLUSIONS

Our findings show that healthy postmenopausal women present an asymmetry between adrenergic nervous system and HPA axis activities under both basal and stress conditions. HRT was able to modify the abnormal adrenergic nervous system activity, most likely by reducing the sympathetic hyperactivity that characterizes menopause.

Pregnancy followed by delivery may affect circulating soluble lectin-like oxidized low-density lipoprotein receptor-1 levels in women of reproductive age

Background/Objective. It is known that menopause or lack of endogenous estrogen is a risk factor for endothelial dysfunction and CAD. Lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) is involved inmultiple phases of vascular dysfunction.The purpose of the current study was to determine the association between soluble LOX-1 (sLOX-1) and pregnancy followed by delivery in women of reproductive age. Materials/Methods. Sixty-eight subjects with pregnancy followed by delivery (group 1) and 57 subjects with nongravidity (group 2) were included in this study. Levels of sLOX-1 were measured in serum by EL SA. Results. Plasma levels of sLOX-1 were significantly lower in Group 1 than Group 2 in women of reproductive age (0.52 ± 0.18 ng/mL and 0.78 ± 0.13, resp., P < 0.001). There were strong correlations between sLOX-1 levels and the number of gravida (r = −0.645, P < 0.001). The levels of sLOX-1 highly correlated with the number of parous (r = −0.683, P < 0.001). Conclusion. Our study demonstrated that serum sLOX-1 levels were associated with pregnancy followed by delivery that might predict endothelial dysfunction. We conclude that pregnancy followed by delivery may delay the beginning and progress of arteriosclerosis and its clinical manifestations in women of reproductive age.

Drospirenone and levonorgestrel in combination with either 30 or 20 mcg ethinylestradiol reduce soluble adhesion molecules in Brazilian women; cross-sectional study

BACKGROUND

The objective of this study was to evaluate the effect of three contraceptive pills containing ethinylestradiol (EE) (20 or 30 mcg) in combination with drospirenone (DRSP) and levonorgestrel (LNG) on plasma concentration of adhesion molecules vascular cell adhesion molecule -1 (VCAM-1), intercellular adhesion molecule-1 (ICAM-1) and E-selectin.

STUDY DESIGN

A cross-sectional study was conducted with 72 participants (18-30 years old) distributed into three groups that used oral contraceptives containing EE 20 or 30 mcg combined with DRSP 3 mg or EE 30 mcg/LNG 150 mcg for at least 6 months. The control group was comprised of nonusers of contraceptives. Soluble VCAM-1, soluble ICAM-1 and soluble E-selectin were evaluated by enzyme-linked immunosorbent assay.

RESULTS

Compared to the control group, a significant decrease was found in VCAM-1 and ICAM-1 concentrations with use of DRSP/20 EE and LNG/30 EE.

CONCLUSIONS

DRSP/20 EE and LNG/30 EE induce favorable changes in endothelial function.

Sympathetic nerve hyperactivity and its effect in postmenopausal women

OBJECTIVES

Hypertension and its subsequent cardiovascular complications have been associated with sympathetic neural activation, and their prevalence in women increases after the menopause. However, there have been no data on the level of sympathetic activation and its relationship to vascular blood flow following the menopause. Therefore, we planned to find out whether the behavior of muscle sympathetic nerve activity (MSNA) and calf blood flow (CBF) in women with and without essential hypertension (EHT) is changed following the menopause.

METHODS

Peroneal nerve activity was measured as mean frequency of single units and of multiunit bursts with simultaneously measured CBF in two matched groups of postmenopausal women with and without EHT in comparison with two matched groups of premenopausal women with and without EHT.

RESULTS

As expected, nerve activity was greater in the hypertensive than in normotensive groups and in postmenopausal than in premenopausal normotensive groups. We found that single unit frequency in postmenopausal hypertensives (65 ± 3.9 impulses/100 cardiac beats) was not significantly different from that in postmenopausal normotensives (54 ± 2.2 impulses/100 cardiac beats) or in premenopausal hypertensives (57 ± 2.8 impulses/100 cardiac beats). Similar results were obtained for burst frequency. In addition, a statistically significant negative correlation between the frequency of nerve activity and CBF was found only in postmenopausal normotensive (at least r =  -0.42, P < 0.04) and hypertensive women (at least r =  -0.45, P < 0.03).

CONCLUSION

These findings suggest that sympathetic nerve hyperactivity in postmenopausal women may have greater vascular effects than in premenopausal women, and could have implications in the management of EHT in postmenopausal women.

Inverted takotsubo cardiomyopathy induced by dobutamine stress echocardiography with atypical presentation

A 48-year-old woman was scheduled by our lab to perform a standard dobutamine/atropine stress echocardiogram. During the test, the patient referred to a slight chest discomfort and developed a progressive left ventricle akinesia of all midbasal LV segments, thus mimicking a midbasal ballooning. ECG persisted without significant abnormalities and with no raise of Troponin I. Coronary angiography showed normal coronary arteries and ventriculography a severe EF reduction and apical hypercontractility. Echocardiography showed a progressive improvement with a complete recovery 48 hours later. This is a rare case of inverted takotsubo syndrome induced by dobutamine stress echocardiography that occurred with atypical presentation.

Cardiovascular hemodynamics during stress in premenopausal versus postmenopausal women

OBJECTIVE

After menopause, women are at an increased risk of cardiovascular disease. The present study assessed cardiovascular hemodynamics in premenopausal versus postmenopausal women, with a focus on systemic vascular resistance (SVR) at rest and during stress. Sympathetic nervous system activity and cardiovascular adrenergic receptor (AR) function were also examined.

METHODS

A total of 90 women (45 premenopausal and 45 postmenopausal) completed a laboratory protocol composed of a resting baseline and four mental stress tasks. Measurements included blood pressure, cardiac output, SVR, and plasma catecholamine level. In addition, alpha- and beta-AR responsiveness to the infusion of selective pharmacological agonists was assessed.

RESULTS

Compared with premenopausal women, postmenopausal women were characterized by similar blood pressure but lower cardiac output and higher SVR, both at rest and during stress (Ps < 0.05). Postmenopausal women also had higher baseline plasma norepinephrine levels (P = 0.007) and reduced beta-AR responsiveness (P = 0.02), although differences in beta-AR responsiveness may have been confounded by aging effects.

CONCLUSIONS

After menopause, women exhibit altered sympathetic nervous system activity and a sustained increase in hemodynamic load that may contribute to pathological structural and functional changes in the heart and blood vessels.

Research into Specific Modulators of Vascular Sex Hormone Receptors in the Management of Postmenopausal Cardiovascular Disease

Cardiovascular disease (CVD) is more common in men and postmenopausal women than premenopausal women, suggesting vascular benefits of female sex hormones. Studies on the vasculature have identified estrogen receptors ERα, ERβ and a novel estrogen binding membrane protein GPR30, that mediate genomic and/or non-genomic effects. Estrogen promotes endothelium-dependent relaxation by inducing the production/activity of nitric oxide, prostacyclin, and hyperpolarizing factor, and inhibits the mechanisms of vascular smooth muscle contraction including [Ca(2+)](i), protein kinase C, Rho kinase and mitogen-activated protein kinase. Additional effects of estrogen on the cytoskeleton, matrix metalloproteinases and inflammatory factors contribute to vascular remodeling. However, the experimental evidence did not translate into vascular benefits of menopausal hormone therapy (MHT), and the HERS, HERS-II and WHI clinical trials demonstrated adverse cardiovascular events. The discrepancy has been partly related to delayed MHT and potential changes in the vascular ER amount, integrity, affinity, and downstream signaling pathways due to the subjects' age and preexisting CVD. The adverse vascular effects of MHT also highlighted the need of specific modulators of vascular sex hormone receptors. The effectiveness of MHT can be improved by delineating the differences in phramcokinetics and pharmacodynamics of natural, synthetic, and conjugated equine estrogens. Estriol, "hormone bioidenticals" and phytoestrogens are potential estradiol substitutes. The benefits of low dose MHT, and transdermal or vaginal estrogens over oral preparations are being evaluated. Specific ER modulators (SERMs) and ER agonists are being developed to maximize the effects on vascular ERs. Also, the effects of estrogen are being examined in the context of the whole body hormonal environment and the levels of progesterone and androgens. Thus, the experimental vascular benefits of estrogen can be translated to the outcome of MHT in postmenopausal CVD, as more specific modulators of sex hormone receptors become available and are used at the right dose, route of administration and timing, depending on the subject's age and preexisting cardiovascular condition.

Hematocrit and mean arterial blood pressure in pre- and postmenopause women

The relationship between mean arterial blood pressure (MAP) and hematocrit (Hct) was studied in pre- and postmenopause women in the city of Durango, Mexico. Premenopause women show a negative trend between parameters that is not statistically significant. MAP and Hct are directly related in postmenopause women (p < 0.01). It is proposed that that this MAP/Hct relationship is in part due to differences in endothelial function where menopause decreases the capacity of the endothelium to respond to increased blood viscosity and shears stress, leading to the increased production of vasodilator mediators to compensate for changes in blood viscosity due to changes in Hct. Comparison with a large group of postmenopause women in the city of Stockholm showed identical trends.

Menopause does not affect blood pressure and risk profile, and menopausal women do not become similar to men

OBJECTIVE

Menopause is considered to be a cardiovascular risk factor, but this belief is based on opinions rather than on evidence. Confounding effects of age are often neglected.

DESIGN

Population-based study with further subanalysis of case-to-case age-matched cohorts of men and fertile and menopausal women.

SETTING

Epidemiology in primary, public, institutional frame.

PARTICIPANTS

Nine thousand three hundred and sixty-four men and women aged 18-70 years representative of Italian general population followed-up for 18.8 +/- 7.7 years.

MAIN OUTCOME MEASURES

Blood pressure (BP), prevalence and incidence of hypertension, serum total, high-density lipoprotein and low-density lipoprotein cholesterol, glucose tolerance, body adiposity, vascular reactivity, target organ damage, overall and cardiovascular mortality and morbidity, by gender and by menopausal status.

RESULTS

Cross-sectional: crude BP, pressor response to cold, orthostatic BP decrease, BMI, skinfold thickness, fasting and postload blood glucose and insulin, serum lipids, left ventricular mass, serum creatinine, microalbuminuria and augmetantion index were higher in menopausal than in fertile women, and comparable in menopausal women and men, a difference that was no longer present when adjusting for age or considering age-matched cohorts. Longitudinal: BP increase during follow-up, cardiovascular mortality and morbidity were greater in menopausal than in fertile women, and comparable in menopausal women and men, a difference no longer present in age-matched cohorts. Menopausal status was rejected from multivariate Cox analysis also including age.

CONCLUSION

The cardiovascular effects usually attributed to menopause seem to be a mere consequence of the older age of menopausal women.

Relation between body mass index and endothelium-dependent vasodilatation in healthy postmenopausal women

OBJECTIVE

To evaluate whether endothelium-dependent vasodilatation is related to anthropometric parameters in 105 healthy postmenopausal women 47-68 years of age.

METHODS

Flow-dependent, endothelium-dependent vasodilatation was considered as the maximal dilatation following deflation of a cuff placed on the forearm and inflated to supra-systolic blood pressure values for 4 min. Endothelium-independent vasodilatation was considered as the maximal dilatation induced by sublingual nitroglycerine (400 microg).

RESULTS

Among parameters such as height, weight, body mass index (BMI), waist, hip, waist/hip ratio, lipids, glucose or insulin, only BMI, an indirect index of adiposity, was independently and directly related to baseline brachial artery diameter (b = 0.042, r = 0.269, p = 0.0055) and flow-mediated endothelium-dependent vasodilatation either expressed as net (b = 0.034, r = 0.315, p = 0.001) or percentage (b = 0.376, r = 0.202, p = 0.039) change. Stratification for BMI categories showed that women with BMI < 22 kg/m(2) had an endothelium-dependent vasodilatation, significantly lower than that of women with BMI >or= 30 kg/m(2) (0.711 +/- 0.076 mm vs. 1.107 +/- 0.141 mm; p = 0.0114). BMI was not related to endothelium-independent vasodilatation.

CONCLUSIONS

Present results show that, in healthy postmenopausal women, endothelium-dependent vasodilatation is related to BMI, arteries of slender women dilating less than those of their heavier counterparts. A low BMI does not appear to be beneficial for artery vasodilatation in healthy postmenopausal women.

Effect of Hormone Therapy on Exercise Capacity in Early Postmenopausal Women

OBJECTIVE

To compare the exercise capacity of postmenopausal women with matched premenopausal controls, as well as postmenopausal women before and after 3 months of hormone therapy (HT).

METHODS

This study examined the response to strenuous isotonic exercise in 30 women with recently developed menopause (age, mean+/-standard deviation, 50.6+/-1.1 years) without cardiovascular risk factors or diseases. Thirty premenopausal subjects, matched one-to-one for age and biophysical characteristics, were the control group. Postmenopausal women underwent examination before (T(0)) and 3 months after (T(1)) HT (oral 0.625 mg conjugated estrogen and 2.5 mg medroxyprogesterone acetate/day) with high-resolution ultrasound determination of peripheral flow-mediated vasodilation and an integrative cardiopulmonary test.

RESULTS

Postmenopausal women showed an impairment of flow-mediated vasodilation (P<.001) in the radial artery and a worsening of physical performance, primarily exemplified by lower maximal workload (P<.01) and peak oxygen consumption (Vo(2)max, P<.001) compared with premenopausal women. After 3 months on HT, ergometabolic parameters and vasodilation reserve were at a level comparable to premenopausal women. Flow-mediated vasodilation measurements after 3 months on HT significantly correlated with those of peak oxygen consumption (r=0.77, P<.001) and the ratio between the increase in oxygen consumption and that in work rate (DeltaVo(2)/DeltaWR) (r=0.73, P<.001).

CONCLUSION

The peripheral circulation is the limiting system in postmenopausal women experiencing exercise intolerance, and there are benefits in introducing HT.

Menopause, estrogens, and endothelial dysfunction: current concepts

Menopause is defined as the permanent cessation of menses. Cardiovascular disease is the leading cause of death among postmenopausal women in developed countries. The disparity between the incidence of cardiovascular disease among women in pre- and postmenopause has been ascribed to the actions of endogenous estrogen on the cardiovascular system and, particularly, on the vascular endothelium. The endothelium plays an important role in cardiovascular homeostasis, either through the vascular tonus and its regulation, or through coagulation and the inflammatory response. Endothelial dysfunction is implicated in the genesis of atherosclerosis and other chronic disorders, such as diabetes mellitus and hypertension. The pharmacological use of estrogen exerts influence on the circulating levels of markers of vascular tonus, and inflammation, as well as prothrombotic, and fibrinolytic markers, but the impact of these changes on the atherosclerotic disease is still uncertain.

Heart rate variability in young women with polycystic ovary syndrome

BACKGROUND

Limited data are available related to the effects of sex hormones on cardiac autonomic function. Few studies investigated the heart rate variability (HRV) parameters during regular menstrual cycle or in postmenopausal women using hormone replacement therapy, but the results were contradictory. The aim of the study was to compare the characteristics of the autonomic innervation of the heart in polycystic ovary syndrome (PCOS) patients with regularly cycling controls.

METHODS

Thirty PCOS patients and 30 healthy regularly cycling controls were included in the study. Groups were compared with respect to age and various cardiovascular risk factors. Characteristics of autonomic innervation of the heart were evaluated with HRV. Power spectral analysis of HRV was performed to calculate the low frequency peak (LF 0.04-0.15 Hz), high-frequency peak (HF 0.15-0.40 Hz), LF in normalized unit (LF nu), HF in normalized unit (HF nu) and LF/HF ratio.

RESULTS

PCOS patients had adverse cardiovascular risk profile than controls. As the HRV parameters, PCOS patients had significantly higher LF nu (P = 0.005) and LF/HF ratio (P = 0.001) and significantly lower HF (P = 0.006) and HF nu (P < 0.001) compared to controls.

CONCLUSION

Autonomic innervation of the heart can be affected in PCOS with increased sympathetic and decreased parasympathetic components of HRV. As a result, sympathetic to parasympathetic ratio may increase in PCOS. This finding should be confirmed with larger studies also evaluating the clinical implications of altered HRV parameters.

Evidence against a role for ovarian hormones in the regulation of blood flow

OBJECTIVE

To determine the effect of ovarian hormone deficiency on peripheral vascular function.

DESIGN

Randomized, single-blind, placebo-controlled.

SETTING

General clinical research center.

PATIENT(S)

Twelve healthy, lean, premenopausal women with regular menstrual cycles.

INTERVENTION(S)

Measurements were made during the early to midfollicular and midluteal phases of the menstrual cycle. Patients were then randomized to an 8-week course of gonadotropin-releasing hormone agonist (GnRHa) (n = 6) or placebo (n = 6) and retested. On each occasion, blood flow was assessed in the basal postabsorptive state and under euglycemic-hyperinsulinemic-hyperaminoacidemic conditions.

MAIN OUTCOME MEASURE(S)

Calf blood flow by venous occlusion plethysmography.

RESULT(S)

No differences in calf blood flow under postabsorptive (1.65 +/- 0.09 vs. 1.73 +/- 0.16 mL/100 g tissue per minute) or insulin-stimulated conditions (2.24 +/- 0.20 vs. 2.30 +/- 0.18 mL/100 g tissue per minute) were found between the follicular and luteal phases of the menstrual cycle, respectively; therefore, pretreatment data were averaged. Ovarian hormone suppression did not alter postabsorptive calf blood flow (GnRHa: 1.68 +/- 0.13 to 1.69 +/- 0.15; placebo: 1.69 +/- 0.21 to 1.64 +/- 0.14 mL/100 g tissue per minute) or the blood flow response to insulin infusion (GnRHa: 2.40 +/- 0.21 to 2.37 +/- 0.29; placebo: 2.10 +/- 0.28 to 2.19 +/- 0.35 mL/100 g tissue per minute).

CONCLUSION(S)

Variation in ovarian hormones associated with the menstrual cycle or short-term ovarian hormone deficiency induced by GnRHa do not affect calf blood flow under postabsorptive conditions or the response to hyperinsulinemia.

The effect of raloxifene on cardiac autonomic regulation in osteoporotic women

OBJECTIVE

There are suggestive data that raloxifene may have favorable effects on the arterial systems in postmenopausal women and thereby lowering the incidence of future adverse cardiovascular events. Reduction of heart rate variability appears to be a marker for identifying subjects with an increased risk for cardiac mortality, particularly in patients after myocardial infarction and in elderly people. Although there are conflicting data with regard to the effects of estrogen and progesterone on heart rate variability in postmenopausal women, the impact of raloxifene treatment on heart rate variability is fully unknown.

STUDY DESIGN

Forty-three osteoporotic postmenopausal women were recruited in a prospective, randomized, and placebo-controlled 6-month study. Of these women, 23 received raloxifene hydrocloride, 60 mg once daily, whereas 20 women received alendronate, 10 mg daily. Time and frequency domains of heart rate variability were measured at baseline and at 3 months and 6 months of the treatment.

RESULTS

Time domain indices of heart rate variability, mean RR, and SD of all beat-to-beat intervals remained identical within the groups at the end of treatment. The square root of the mean of the sum of squares of successive RR intervals, a sensitive index of parasympathetic activity, tended to increase with raloxifene. Frequency domain indices of heart rate variability were as follows: low-frequency power of heart rate variability tended to stay the same, compared with the baseline values in both treatment regimens. High-frequency power of heart rate variability increased significantly in the raloxifene group (P = .039) at 3 months, and this significance persisted at the end of the treatment. A nonsignificant decrease was observed in the alendronate group. Accordingly, the low-frequency power/high-frequency power ratio, an index of sympathovagal balance, decreased significantly by the raloxifene treatment (P = .028) at 3 months and persisted at 6 months. There was no significant change in low-frequency power/high-frequency power ratio of patients taking alendronate.

CONCLUSION

Raloxifene seems to have a positive effect on cardiac autonomic regulation in postmenopausal osteoporotic women. This observation could at least partially explain the reduced cardiovascular events in the subset of women with increased cardiovascular risk in the Multiple Outcomes of Raloxifene Evaluation trial. However, the results of ongoing studies should be awaited to have a conclusion of its effects on the cardiovascular system.

Impairment of physical exercise capacity in healthy postmenopausal women

BACKGROUND

Healthy postmenopausal women reveal a series of peripheral vascular abnormalities, whose possible consequences on exercise performance has not been yet elucidated.

METHODS

We studied the response to strenuous exercise in 25 postmenopausal women (mean age 50 +/- 3 years) without cardiovascular risk factors or disease through an integrative cardiopulmonary test.

RESULTS

In comparison with 25 premenopausal subjects matched for age and biophysical characteristics, postmenopausal women showed a lower maximal workload (P < .01) and maximum VO2 (P < .01), an early anaerobic threshold (P < .05), and a lower ratio between increase of VO2 consumption and work rate (P < .01).

CONCLUSIONS

Our results suggest that menopause could represent an important concomitant cause in determining an impairment of exercise capacity. The set of cardiopulmonary abnormalities found in the present study seems to identify the peripheral circulation as the limiting system in postmenopausal women experiencing exercise intolerance. Finally, present findings are in favor of an early introduction of postmenopausal hormone replacement therapy.

Insulin resistance and sympathetic overactivity in women

Insulin sensitivity decreases for the first time in females at the time of menarche. A much more profound decrease in insulin sensitivity is observed at the end of pregnancy. This physiological insulin resistance is not accompanied by a rise in overall sympathetic activity as reflected in plasma noradrenaline levels, but there is evidence of moderate sympathetic overactivity in muscle and the heart. Pre-eclampsia is characterized by increased insulin resistance, sympathetic overactivity and a particular lipid profile. Thus it is the first manifestation of metabolic syndrome. Women with a history of pre-eclampsia have persistent insulin resistance after pregnancy associated with increased sympathetic activity of the cardiovascular system, and coronary artery disease later in life. Aging is accompanied by a greater increase in sympathetic traffic in women than in men, and inflammation (measured via C-reactive protein) seems to be more strongly related to metabolic syndrome in women than in men. The clinical relevance of these observations remains to be shown. As the key factors of metabolic syndrome, such as insulin resistance and sympathetic overactivity, are closely inter-related, treatment should be aimed at cutting the vicious circle at many points: lifestyle modification (diet, increasing exercise) as a basis of therapy, use of insulin sensitizers (e.g. metformin) to decrease insulin resistance, central sympatholytics (e.g. moxonidine), and AT-receptor blockers or angiotensin-converting enzyme (ACE) inhibitors to overcome sympathetic overactivity, hypertension and inflammation.

Long term effects of hormone replacement therapy on heart rate variability, QT interval, QT dispersion and frequencies of arrhythmia

BACKGROUND

The aim of the study was to investigate the effects of a long term (1 year) hormone replacement therapy (HRT) on QT interval, QT dispersion (QTd) frequencies of arrhythmia and heart rate variability (HRV) parameters.

METHODS

Forty-six healthy postmenopausal women (mean age; 55.34+/-4.21) as a hormone replacement therapy group and 25 healthy premenopausal women (mean age; 35.36+/-6.06) as a control group were prospectively enrolled to the study. Hormone replacement therapy group was divided into two groups; estrogen replacement therapy (ERT) group (n=23) and progestin-estrogen replacement therapy (PERT) group (n=23). Standard 12 lead electrocardiograms and 24-h ambulatory Holter recording were obtained to evaluate the effects of one year of ERT and PERT on QT intervals, QTd, frequencies of arrhythmias and HRV parameters.

RESULTS

Long term use of ERT increases QT interval, QTd, in the frequencies of arrhythmia and HRV indexes of parasympathetic activity; however, the increase in frequencies of arrhythmia was not statistically significant (p>0.05). Long term use of PERT did not effected QT interval, QTd, frequencies of ventricular arrhythmia and HRV parameters (p>0.05). Frequency of supraventricular tachycardia increased in post-treatment PERT group was compared with pre-treatment PERT group.

CONCLUSION

These findings supported the hypothesis that estrogen may directly modulate ventricular repolarization. But progestin do not effect the ventricular repolarization. However, these findings must be supported with a large-scale study.

Effects of low-dose continuous combined HRT on vascular function in women with type 2 diabetes

BACKGROUND

Improvement in vascular endothelial function is widley cited as a beneficial effect of hormone replacement therapy (HRT). Women with type 2 diabetes (T2DM) are at increased cardiovascular risk and have impaired endothelial function. Any benefits of HRT on endothelial function in this group are of particular interest.

OBJECTIVES

We assessed effects on vascular function of oral 17beta oestradiol (1 mg) and norethisterone (0.5 mg) in postmenopausal women with T2DM.

DESIGN

Double-blind, randomised, placebo-controlled trial.

ASSESSMENTS

Twenty-eight women had pulse wave velocity (PWV) and adhesion molecules VCAM-1 and ICAM-1 assessed before and after three months' treatment. Twenty-four women also had gluteal fat biopsy for assessment of resistance vessel function (using wire myography).

RESULTS

HRT did not affect PWV, VCAM-1, ICAM-1 or carbachol response. Effects of L-NAME and indomethacin on carbachol sensitivity were similar in both groups.

CONCLUSIONS

This HRT preparation had no detectable effect on these measures of endothelial function in women with T2DM.

Oestrogen increases myocardial blood flow in men: assessment by 13N-ammonia positron emission tomography

OBJECTIVES

Oestrogen has been shown to increase nitric oxide-mediated vasodilatation and modulate sympathetic tone in postmenopausal women. We investigated the acute effects of oestrogen on the coronary microcirculation in men.

METHODS

Myocardial blood flow was quantified using N-ammonia positron emission tomography before and 20 min after an intravenous administration of conjugated oestrogen (10 mg) in nine healthy men.

RESULTS

There were no significant changes in either systemic blood pressure or heart rate before and after oestrogen infusion. However, myocardial blood flow was increased by oestrogen from 0.88 +/-0.06 to 1.05+/-0.09 ml x g x min (P<0.05). Although serum levels of nitrite/nitrate (end products of nitric oxide) were not increased, circulating norepinephrine (noradrenaline) levels were decreased after the administration of oestrogen from 401+/-114 to 346+/-112 pg x ml (P<0.01). A significant negative correlation was found between myocardial blood flow and plasma norepinephrine levels (r=-0.67, P<0.05).

CONCLUSIONS

A single administration of oestrogen enhanced myocardial circulation in healthy men. The oestrogen-induced increase in myocardial blood flow may be due to direct effects on the coronary circulation or through the modulation of norepinephrine levels, rather than the production of nitric oxide.

Impaired cardiac response to exercise in post-menopausal women: relationship with peripheral vascular function

Endothelial dysfunction has been demonstrated in post-menopausal women. To assess the relationship between peripheral vascular reserve and cardiac function during exercise in post-menopausal women, 91 subjects, who had no ischaemic findings on myocardial SPECT, were assigned to four groups: pre-menopausal women (n=13), post-menopausal women (n=33), younger men aged < or =50 years (n=10), and older men aged >50 years (n=35). First-pass radionuclide angiography was performed before and during bicycle exercise to calculate ejection fraction (EF) and peripheral vascular resistance (VR). There were no differences in haemodynamic variables among the groups at baseline. The per cent increase in EF=(exercise EF - resting EF)x100/resting EF, and the per cent decrease in VR=(resting VR - exercise VR)x100/resting VR were depressed in the post-menopausal women (0.4+/-2% and 35+/-3%, respectively) compared to the pre-menopausal women (10+/-3% and 47+/-3%, respectively; P<0.05 each). Although the age dependent impairment is thought to cause this depression, neither the per cent increase in EF nor the per cent decrease in VR in the older men was significantly different from that in the younger men. Post-menopausal women exhibited depressed cardiac function during exercise, which may be related to the impairment of peripheral vascular function after menopause.

Effect of atorvastatin on endothelium-dependent vasodilation in postmenopausal women with average serum cholesterol levels

After menopause, most healthy women show an impairment of peripheral vasodilation and an increase of plasma cholesterol levels. Statins have been shown to improve endothelial function in hypercholesterolemic men and women. The present study tests whether atorvastatin (10 mg) influences endothelium-dependent vasodilation in postmenopausal normocholesterolemic women. Twenty-eight healthy, postmenopausal women (mean age 51 +/- 2 years) with serum total cholesterol and low-density lipoprotein cholesterol within the desirable range entered a double-blind, single-crossover study. Postmenopausal women were randomized to receive either atorvastatin (10 mg/day) or placebo for 10 days and then crossed to the complementary treatment. Endothelium-dependent and -independent responses were assessed by means of strain-gauge plethysmography before and after intra-arterial infusion of acethylcholine (ACh) and sodium nitroprusside, in comparison to physiologic saline. The nitric oxide pathway was evaluated by repeating the infusion of ACh during admininstration of L-arginine and (G)-monomethyl-L-arginine (L-NMMA). Serum lipoproteins were not significantly modified by the active treatment. The vasodilation induced by ACh was significantly higher in the atorvastatin-treated women compared with the placebo-treated group (24 +/- 3 vs 13 +/- 2 ml/100 ml tissue/min, p <0.01). In contrast, responses to the endothelium-independent vasodilator sodium nitroprusside were not significantly modified by atorvastatin. The ACh-stimulated vasodilation induced by atorvastatin was additionally potentiated by L-arginine (800 +/- 105% vs 370 +/- 60%, p <0.05) and blunted by L-NMMA. No correlation was found between changes in plasma cholesterol and improvement in forearm blood flow. Our data show that the beneficial effect of atorvastatin on endothelium-dependent vasodilation is independent from changes in the lipid profile.

Effects of oestrogen replacement on steady and pulsatile haemodynamics in ovariectomized rats

1. The effects of ovariectomy (Ovx), menopause and oestrogen replacement on the haemodynamics remain controversial. The present study employed the technique of arterial impedance analysis to measure and calculate the steady and pulsatile haemodynamics. The purpose was to determine the haemodynamic consequence of ovariectomy and oestrogen replacement. 2. Ovariectomy was carried out under anaesthesia on female Sprague Dawley rats aged 9 weeks. Oestrogen (17 beta-estradiol or E(2)) replacement started 1 week after ovariectomy for 4 weeks. Ovx increased the body weight (BW), while it greatly reduced the uterus weight. Left ventricular weight (LVW) was slightly increased, but LVW/BW ratio was slightly reduced. These changes were reversed after E(2) replacement. 3. Compared to sham group, Ovx with or without E(2) replacement did not significantly affect the systolic, mean and diastolic pressure. In Ovx, pulse pressure (PP) and heart rate were significantly increased, while stroke volume and cardiac output were slightly decreased. Total peripheral resistance (TPR) was largely elevated, indicating Ovx induced systemic vasoconstriction. These changes all returned to close normal values (sham group) after E(2) replacement, except PP. 4. Ovx increased the characteristic input impedance (Zc) and pulse wave reflection, while it decreased arterial compliance. E(2) treatment reversed these changes, except Zc. 5. These results demonstrate that Ovx influences both the resistance and Windkessel functions of the artery. E(2) treatment effectively reverses most the effects of Ovx both on the steady and pulsatile haemodynamics.

Effect of estrogen replacement therapy on insulin sensitivity of glucose metabolism and preresistance and resistance vessel function in healthy postmenopausal women

In the present study, we hypothesized that estradiol, via its ability to vasodilate in an endothelium-dependent manner, might enhance vascular effects of insulin. Basal and insulin-stimulated peripheral blood flow and resistance, arterial stiffness, and glucose metabolism were determined in 27 healthy postmenopausal women before and after 12 weeks of treatment with either transdermal or oral estradiol or corresponding placebo preparations. Whole body insulin sensitivity was determined using the euglycemic insulin clamp technique (rate of continuous insulin infusion 1 mU/kg.min), forearm blood flow with a strain-gauge plethysmography, and arterial stiffness using pulse wave analysis. Estradiol therapy increased basal peripheral blood flow (1.5 +/- 0.1 vs. 1.9 +/- 0.1 mL/dL.min, 0 vs. 12 weeks; P: < 0.01), decreased peripheral vascular resistance (65 +/- 3 vs. 52 +/- 3 mm Hg/mL/dL.min, respectively; P: < 0.01), and diastolic blood pressure (78 +/- 2 vs. 75 +/- 2 mm Hg, respectively; P: < 0.05) but had no effect on large artery stiffness. Infusion of insulin did not acutely alter peripheral blood flow but diminished large artery stiffness significantly both before and after the 12-week period of estradiol therapy. No measure of acute insulin action (glucose metabolism, blood flow, or large artery stiffness) was altered by estradiol or placebo treatment. These data demonstrate that insulin and estradiol have distinct hemodynamic effects. Physiological doses of estradiol increase peripheral blood flow but have no effects on large artery stiffness, whereas physiological concentrations of insulin acutely decrease stiffness without changing peripheral blood flow. Putative vasculoprotection by estradiol is, thus, not mediated via alterations in arterial stiffness or insulin sensitivity.

Evidence of a role of endogenous estrogen in the modulation of autonomic nervous system

We studied heart rate variability in 14 healthy women before and after oophorectomy compared with 14 matched women who underwent hysterectomy with ovarian conservation. Surgical menopause induced a decline in cardiac vagal modulation with a shift toward sympathetic hyperactivity. Recovery of the baseline condition after 3 months of estrogen replacement therapy in oophorectomized women suggests a role of estrogen in the autonomic nervous control of the cardiovascular system.

Effects of acute administration of natural progesterone on peripheral vascular responsiveness in healthy postmenopausal women

Peripheral vascular responses to acute administration of natural progesterone were studied in 12 postmenopausal women (mean +/- SD age 50.3 +/- 4.8 years) with no evidence of cardiovascular disease. According to a randomized, double-blind protocol, all subjects were given natural progesterone as a vaginal cream, able to produce a rapid peak and decay of plasma hormone concentrations, or matched placebo, with crossover after a 1-week washout period. Forearm blood flow and peak flow after ischemic stress (ml/100 ml/min), local vascular resistance (mm Hg/ml/100 ml/min), venous volume (ml/100 ml), and venous compliance (ml/100 ml/mm Hg) were measured by strain-gauge venous occlusion plethysmography at baseline and after progesterone or placebo administration. Plasma norepinephrine concentrations were determined by high-performance liquid chromatography with electrochemical detection. Progesterone sharply decreased forearm blood flow (p <0.01) through an increase in local vascular resistance (p <0.01). Measures of venous function remained unchanged. Although the hormone increased circulating norepinephrine concentrations (p <0.05), there were no significant changes in mean arterial pressure or heart rate. Furthermore, progesterone reduced the local vasodilator capacity, shown by a decrease in forearm delta flow (difference between peak flow and basal flow, p <0.05). Compared with the well-known effect of estrogen, progesterone exerted an opposite action on peripheral vascular responsiveness. Peripheral circulatory changes may be attributed to a direct activity of progesterone on the arterial wall and may in part reflect a modulation of the hormone on peripheral sympathetic tone. Consideration must be given to the hypothesis that the addition of progestin may attenuate the beneficial effects of unopposed estrogen replacement therapy in postmenopausal women.