Data/hora: 11/06/2024 06:30:33

Provedor de dados: 	Brazilian Journal of Medical and Biological Research	
País: 	Brazil	
Título: 	Autonomic modulation of heart rate of young and postmenopausal women undergoing estrogen therapy	
Autores: 	Neves,V.F.C.; Silva de Sá,M.F.; Gallo Jr.,L.; Catai,A.M.; Martins,L.E.B.; Crescêncio,J.C.; Perpétuo,N.M.; Silva,E.	
Data: 	2007-04-01	
Ano: 	2007	
Palavras-chave: 	Heart rate variability; Aging; Menopause; Estrogen therapy.	
Resumo: 	The aim of the present study was to determine whether estrogen therapy (ET) reduces alterations of the autonomic control of heart rate (HR) due to hypoestrogenism and aging. Thirteen young (24 ± 2.6 years), 10 postmenopausal (53 ± 4.6 years) undergoing ET (PM-ET), and 14 postmenopausal (56 ± 2.6 years) women not undergoing ET (PM) were studied. ET consisted of 0.625 mg/day conjugated equine estrogen. HR was recorded continuously for 8 min at rest in the supine and sitting positions. HR variability (HRV) was analyzed by time (SDNN and rMSSD indices) and frequency domain methods. Power spectral components are reported as normalized units (nu) at low (LF) and high (HF) frequencies, and as LF/HF ratio. Intergroup comparisons: SDNN index was higher in young (median: supine, 47 ms; sitting, 42 ms) than in PM-ET (33; 29 ms) and PM (31; 29 ms) women (P &lt; 0.05). PM showed lower HFnu, higher LFnu and higher LF/HF ratio (supine: 44, 56, 1.29; sitting: 38, 62, 1.60) than the young group in the supine position (61, 39, 0.63) and the PM-ET group in the sitting position (57, 43, 0.75; P &lt; 0.05). Intragroup comparisons: HR was lower in the supine than in the sitting position for all groups (P &lt; 0.05). The HRV decrease from the supine to the sitting position was significant only in the young group. These results suggest that HRV decreases during aging. ET seems to attenuate this process, promoting a reduction in sympathetic activity on the heart and contributing to the cardioprotective effect of estrogen hormones.	
Tipo: 	Info:eu-repo/semantics/article	
Idioma: 	Inglês	
Identificador: 	http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2007000400007	
Editor: 	Associação Brasileira de Divulgação Científica	
Relação: 	10.1590/S0100-879X2006005000080	
Formato: 	text/html	
Fonte: 	Brazilian Journal of Medical and Biological Research  v.40 n.4 2007	
Fonte: 	info:eu-repo/semantics/openAccess