Decrease of serum endothelin levels with postmenopausal hormone replacement therapy or tibolone

Endothelin is the most potent vasoconstrictor peptide known to date. Hormon e replacement therapy (HRT) with estrogen reduces plasma endothelin levels. We measured endothelin in 51 postmenopausal patients before and during HRT . Patients were randomly allocated to receive either oral tibolone, oral or transdermal 17 beta-estradiol. A group of comparable volunteers served as controls. After 24 months, endothelin levels decreased in all treatment gro ups: tibolone, 18.2%; oval 23.1%; transdermal, 20.8%. Endothelin levels inc reased in the controls by 36.6% (p < 0.01). Tibolone decreases endothelin l evels to a similar degree as conventional estrogen-progestogen-replacement therapy. These data provide another potential mechanism supporting the card ioprotective effects of tibolone.