Postmenopausal hormonal replacement decreases plasma levels of endothelin-1.
Hormone replacement therapy (HRT) protects against cardiovascular disorders, but the mechanisms of this action are poorly understood. We assessed the plasma levels of vasoconstrictive endothelin-1 (ET-1) in 26 healthy postmenopausal women before and during HRT. The women were randomized to receive either continuous transdermal (estradiol 50 ug/24 hrs) complemented with periodic 12 days' courses with medroxyprogesterone (10.0 mg/day)(n = 13) or continuous oral estradiol (2.0 mg/day) and continuous norethisterone acetate (1.0 mg/day)(n = 13). ET-1 was measured with specific radioimmunoassay after concentrating the sample with solid phase extraction. Pretreatment plasma ET-1 (1.28 +/- 0.36 pmol/ml, mean +/- SD) in the whole study group decreased (p < 0.01) to 1.05 +/- 0.26 pmol/ml at 6 months and to 1.10 +/- 0.32 pmol/ml at 12 months of treatment. A subgroup analysis between the two HRT regimens revealed no significant differences in the response of plasma ET-1 to HRT. These first data on HRT-induced reduction in plasma ET-1 may provide a new explanation for the cardiovascular protection by HRT.
Ylikorkala
O
O
Department of Obstetrics and Gynecology, Helsinki University Central Hospital, Finland.
Orpana
A
A
Puolakka
J
J
Pyörälä
T
T
Viinikka
L
L
D000279:Administration, Cutaneous; D000284:Administration, Oral; D016232:Endothelins / Q000097:blood*; D004958:Estradiol / Q000097:blood; D015914:Estrogen Replacement Therapy; D005260:Female; D006801:Humans; D008875:Middle Aged; D017698:Postmenopause / Q000097:blood*
D016232:Endothelins; D004958:Estradiol