title: The effect of the menstrual cycle and of ethinylestradiol on nitric oxide, endothelin-1 and homocysteine plasma levels.
abstract: The use of the estrogen ethinylestradiol is associated with an increased cardiovascular risk. It is not known whether this might be caused by an influence of ethinylestradiol on endothelium-derived factors or on the cardiovascular risk factor homocysteine. Our aim was to evaluate whether a short-term treatment with ethinylestradiol results in changes of nitric oxide (NO), endothelin-1 and homocysteine. Participants were ten healthy women with regular menstrual cycles. NO, homocysteine, endothelin-1, estradiol and progesterone were measured during one cycle and before and after treatment with ethinylestradiol at 50 microg/day. Homocysteine and NO did not change significantly during the menstrual cycle or after treatment. However, endothelin-1 levels decreased during the cycle (from 3.89 ng/l to 2.93 ng/l p < 0.05) and after ethinylestradiol (from 2.94 ng/l to 2.26 ng/l p<0.03). Analysis of the pretreatment data showed a positive correlation between homocysteine and NO and between NO and endothelin-1. Treatment with ethinylestradiol caused a shift in the balance between NO and endothelin-1 in the direction of vasodilatation. This finding is one factor concerning the effects of ethinylestradiol on the vascular system but does not explain the cardiovascular risk of this substance.
authors.affiliation: Clinic of Endocrinology, Department of Gynecology and Obstetrics, University Hospital, Zürich, Switzerland. gabriele.merki@fhk.usz.ch
authors.forename: G S
authors.initials: GS
authors.lastname: Merki-Feld
authors.forename: B
authors.initials: B
authors.lastname: Imthurn
authors.forename: P J
authors.initials: PJ
authors.lastname: Keller
mesh_terms: D000328:Adult; D002318:Cardiovascular Diseases; D019332:Endothelin-1 / Q000097:blood*; D004997:Ethinyl Estradiol / Q000009:adverse effects / Q000494:pharmacology*; D005260:Female; D006710:Homocysteine / Q000097:blood*; D006801:Humans; D008597:Menstrual Cycle / Q000502:physiology*; D009569:Nitric Oxide / Q000097:blood*; D012307:Risk Factors; D014664:Vasodilation / Q000187:drug effects
chemical_list: D019332:Endothelin-1; D006710:Homocysteine; D009569:Nitric Oxide; D004997:Ethinyl Estradiol