Submitted on October 22, 2007
Accepted on August 29, 2008
Low-Dose Estrogen Therapy Does Not Change Postexercise Hypotension, Sympathetic Nerve Activity Reduction, and Vasodilation in Healthy Postmenopausal Women
Bruna Oneda1, Claudia Lucia de Moraes Forjaz2, Fernanda Rocci Bernardo1, Tatiana Gouveia Araujo1, Josiane Lima Gusmao1, Eliana Labes3, Sandra Abrahao1, Decio Mion Jr.1, Angela Maggio Fonseca3, and Tais Tinucci2*
1 Hypertension Unit, University of Sao Paulo, Sao Paulo, Brazil
2 Exercise Hemodynamic Laboratory, School of Physical Education and Sport - University of Sao Paulo, Sao Paulo, Brazil
3 Gynecology and Climacteric Service, General Hospital, University of Sao Paulo, Brazil
* To whom correspondence should be addressed. E-mail: ttinucci{at}usp.br.
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 = 9, 1 mg/day) or placebo (n = 9) for six months. They then participated in one 45-min exercise session (cycle ergometer at 50% of VO2 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. Forearm vascular resistance (FVR) was calculated. Data were analyzed using two-way ANOVA. Although postexercise physiological responses were unaltered, HR was significantly lower in the estrogen group than in the placebo group (59 ± 2 vs. 71 ± 2 bpm, P 
0.01). In both groups, exercise produced significant decreases in systolic BP (145 ± 3 vs. 154 ± 3 mmHg, P = 0.01), diastolic BP (71 ± 3 vs. 75 ± 2 mmHg, P = 0.04), mean BP (89 ± 2 vs. 93 ± 2 mmHg, P = 0.02), MSNA (29 ± 2 vs. 35 ± 1 bursts/min, P 0.01) and FVR (33 ± 4 vs. 55 ± 10 units, P = 0.01), whereas it increased FBF (2.7 ± 0.4 vs. 1.6 ± 0.2 ml·min-1·100 ml-1, P = 0.02) and did not change HR (64 ± 2 vs. 65 ± 2 bpm, P = 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.
