Acute effects of transdermal estradiol administration on plasma levels of nitric oxide in postmenopausal women

Objective: To investigate the acute effects of transdermal E(2) administration on nitric oxide (NO) plasma levels in postmenopausal women. Design: Randomized, placebo-controlled trial. Setting: Normal human volunteers in an academic research environment. Patient(s): Twenty healthy postmenopausal women. Intervention(s): Transdermal administration of 100 mu g/d E(2) Or placebo. Main Outcome Measure(s): Plasma concentrations of NO stable oxidation products and serum concentrations of E(2) were assessed before and 24 hours after the administration. Result(s): In the group treated with E(2) mean concentration of NO metabolites 24 hours after patch application (37.31 +/- 7.62 mu mol/L) resulted significantly higher than baseline (21.04 +/- 5.71 mu mol/L) and the control group (23.50 +/- 4.03 mu mol/L). The correlation between the mean percent increase in NO metabolites and absolute E(2) concentrations 24 hours after the E(2) administration was statistically significant. Conclusion(s): Transdermal administration of E(2) to healthy postmenopausal women increases the plasma levels of NO and this supports the hypothesis that a NO-related mechanism may contribute to the cardiovascular protective effect of estrogens in postmenopause.