Low-dose estrogen therapy does not change postexercise hypotension, sympathetic nerve activity reduction, and vasodilation in healthy postmenopausal women

Abstract

The aim of this study was to determine whether estrogen therapy enhances postexercise muscle sympathetic nerve activity (MSNA) decrease and vasodilation, resulting in a greater postexercise hypotension. Eighteen postmenopausal women received oral estrogen therapy (ET; n ϭ 9, 1 mg/day) or placebo (n ϭ 9) for 6 mo. They then participated in one 45-min exercise session (cycle ergometer at 50% of oxygen uptake peak) and one 45-min control session (seated rest) in random order. Blood pressure (BP, oscillometry), heart rate (HR), MSNA (microneurography), forearm blood flow (FBF, plethysmography), and forearm vascular resistance (FVR) were measured 60 min later. FVR was calculated. Data were analyzed using a two-way ANOVA. Although postexercise physiological responses were unaltered, HR was significantly lower in the ET group than in the placebo group (59 Ϯ 2 vs. 71 Ϯ 2 beats/min, P Ͻ 0.01). In both groups, exercise produced significant decreases in systolic BP (145 Ϯ 3 vs. 154 Ϯ 3 mmHg, P ϭ 0.01), diastolic BP (71 Ϯ 3 vs. 75 Ϯ 2 mmHg, P ϭ 0.04), mean BP (89 Ϯ 2 vs. 93 Ϯ 2 mmHg, P ϭ 0.02), MSNA (29 Ϯ 2 vs. 35 Ϯ 1 bursts/min, P Ͻ 0.01), and FVR (33 Ϯ 4 vs. 55 Ϯ 10 units, P ϭ 0.01), whereas it increased FBF (2.7 Ϯ 0.4 vs. 1.6 Ϯ 0.2 ml ⅐ min Ϫ1 ⅐ 100 ml Ϫ1 , P ϭ 0.02) and did not change HR (64 Ϯ 2 vs. 65 Ϯ 2 beats/min, P ϭ 0.3). Although ET did not change postexercise BP, HR, MSNA, FBF, or FVR responses, it reduced absolute HR values at baseline and after exercise. postmenopause; aerobic exercise; muscle sympathetic nerve activity; blood pressure THE POSTMENOPAUSAL PERIOD is accompanied by a number of physiological alterations (49). In postmenopausal women, blood pressure gradually increases (71), resulting in a considerably higher incidence of hypertension than that seen in premenopausal women (68). This difference has been attributed to abnormalities in arteriolar resistance caused by the absence of estrogen (48) and/or by physiological aging (1). Arteriolar resistance and hypertension are usually associated with an increase in sympathetic activity or responsiveness (33,64). However, the effects of menopause on sympathetic activity remain unclear. One recent study evaluated Polish and American women between 40 and 56 yr of age (50). The authors found that sympathetic activity in the postmenopausal women was similar to that observed in the premenopausal women. In contrast, the authors of a study conducted in Japan (46) observed higher sympathetic nerve activity in post-and premenopausal middle-aged women. Discrepancies in results might be related to many factors, such as ethnic background and diet.Postmenopausal women are often treated with hormone replacement therapy to minimize the symptoms and consequences of menopause. However, the effects of this therapy depend on the type and dose of hormone employed (31). Currently, many women are receiving natural estrogens, and the North American Menopause Society recommends that hormone replacement therapy should be administered in low doses to avoid any possible side effects (...

Post-Exercise Hypotension Is Mediated by a Decrease in Sympathetic Nerve Activity in Stages 2-3 CKD

“…In addition, Floras et al [20] observed a reduction in the MSNA in borderline hypertensives after 45 min of treadmill exercise at 70% of resting HR. In our lab, previous studies also showed lower MSNA after cycle ergometer exercise (45 min at 50% of VO 2peak ) in normotensive men [35] and post-menopausal women [28] .…”

“…These reductions have been associated with a significant decrease in blood pressure (BP), which has been called in literature 'post-exercise hypotension' [24] , and has been documented in different populations [25,26] , such as normotensive [21,22,[27][28][29][30] and hypertensive [20,[31][32][33] individuals. In hypertensives, post-exercise hypotension has been accepted as a clinically relevant phenomenon because decrease in BP values after exercise has significant magnitude and lasts for many hours [24] .…”

Post-exercise hypotension of normotensive young men through track running sessions

“…The PEH is evidenced after different stimuli, as seen in studies that used aerobic exercise 1 or resistance exercise 3,4 , both in male 5 and female6 subjects and different. However, most of the researches is targeted to middle-aged and elderly people [7][8][9] and who have some pathology, such as hypertension 10,11 , diabetes mellitus 12,13 or chronic kidney disease 14 . This tendency is associated with the fact that the PEH is currently considered a pivotal non pharmacological treatment of hypertension 15,16 , since the individuals with hypertension are at high risk of coronary heart disease, stroke and kidney diseases 17 .…”

Knowing does not imply understanding

“…Although they found an absolute decrease in heart rate both at baseline and after exercise, they were unable to show differences in vascular resistance, flow, blood pressure, or MSNA. 8 The study by Oneda et al 9 in this issue of Menopause moves to thrice-weekly aerobic training in tandem with oral estrogen administration. Again, they were unable to demonstrate any difference in study parameters, including MSNA, with the addition of estrogen.…”