The effect of hormone replacement therapy (HRT) on endothelin-1 and big endothelin levels

Objectives: In the postmenopausal period, the most important reason of the increase in the cardiovascular problems and mortality is the decrease of th e estrogen levels. We aimed to compare the levels of Endothelin-1 (ET-1) an d Big Endothelin (BET), that are secreted as vasoregulators from the vascul ar endothelial cells and cause vasoconstriction, in postmenopausal women, b efore and after the hormone replacement therapy (HRT). Materials and Method s: In this study, 26 postmenopausal women whose blood ET-1 and BET levels c an be measured were included. Eleven of these women had hysterectomy and bi lateral salphin-goopherectomy operation and 15 of them were in natural post menopausal period with at least 12 months since the last menstrual period. The biochemical profile has been measured before starting the HRT and on th e 6(th) month of the HRT. ET-1 and BET levels were measured in RIA Laborato ry. Results: The average level of ET-1 was 5.4 +/- 0.1 pg/ml, and the level of BET was 9.9 +/- 0.7 pg/ml before the start of the therapy. Eight of the 11 women who had hysterectomy used transdermal estrogen and 3 of them rece ived oral conjugated estrogens. Ten natural postmenopausal women used oral Estradiol-17 Valerate-Cyproteron Acetate (E2V-CA) and 5 other in natural me nopause used oral Estradiol-17 Valerate-Medroxyprogesterone Acetate (E2V-MP A). At the 6(th) month of the treatment the level of ET-1 has been found in women using the transdermal estrogen as 3.9 +/- 0.3 pg/ml (p<0.01), in wom en using oral conjugated estrogens as 4.1 +/- 0.1 pg/ml (p<0.01), in women receiving E2V-CA as 4.3 +/- 0.1 pg/ml (p<0.01) and in those receiving E2V-M PA as 4.3 +/- 0.6 pg/ml (p<0.01). The BET level was found to be 7.9 +/- 0.3 pg/ml (p<0.01) in women using transdermal estrogen, in women receiving ora l conjugated estrogen as 8.2 +/- 0.1 pg/ml (p<0.01), in woman receiving E2V -CA as 8.5 +/- 0.1 pg/ml (p<0.01) and in those receiving E2V-MPA as 8.6 +/- 0.6 pg/ml (p<0.01). Conclusion: The results of the cardioprotective effect of estrogen were found to be impressive. Adding progesterone to the treatm ent, has minimally reduced cardioprotective effect of estrogen that has not been found significant. As a result, the positive effect of HRT on the car diovascular system has been shown once more.