MENSTRUAL CYCLIC VARIATION OF ENDOTHELIUM-DEPENDENT VASODILATION OF THE BRACHIAL-ARTERY - POSSIBLE ROLE OF ESTROGEN AND NITRIC-OXIDE

Estrogens have been reported to influence endothelial functions. This article's aim is to examine whether endothelium-dependent vasodilation of brachial arteries is changed in parallel with the physiological va riation of the ovarian hormones during the menstrual cycle in young he althy female subjects. With high-resolution ultrasonography, we measur ed the diameter and blood flow of brachial arteries at rest, during re active hyperemia, and after sublingual nitroglycerin administration in 15 young healthy female subjects (mean 29.6 +/- 2.6 years). All femal e subjects were studied in each of three different phases of one menst rual cycle (M, menstrual phase; F, follicular phase; L, luteal phase). The increase in arterial diameter during reactive hyperemia was lowes t in the menstrual phase and highest in the follicular phase (4.9 +/- 0.8% in M; 14.1 +/- 0.9% in F; 9.2 +/- 1.1% in L; p < 0.005 between an y two means among the groups). No significant difference was apparent in the percentage of increase in blood flow during reactive hyperemia among the three phases. The percentage of increase in arterial diamete r after nitroglycerin administration also was not significantly differ ent among the three phases of the cycle. The serum estradiol level was lowest in the menstrual phase and was highest in the follicular phase (17.5 +/- 1.6 pg/ml in M, p < 0.0005, M versus F and L; 107.8 +/- 18. 0 pg/ml in F, p < 0.05, F versus L; 74.4 +/- 7.3 pg/ml in L). The seru m level of nitrite-nitrate, measured by the Griess reaction, was highe st in the follicular phase and was lowest in the menstrual phase of th e three different phases (40.4 +/- 7.9 mu mol/l in M, p < 0.01, M vers us F, and p < 0.05, M versus L; 106.7 +/- 17.6 mu mol/l in F, p < 0.05 , F versus L; 62.2 +/- 6.2 mu mol/l int). In conclusion, a significant variation of the endothelium-dependent vasodilation parallels the lev els of serum estradiol and nitrite-nitrate during the menstrual cycle in female subjects.