Objective: To investigate the acute effects of transdermal E2 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 micrograms/d E2 or placebo.
Main outcome measure(s): Plasma concentrations of NO stable oxidation products and serum concentrations of E2 were assessed before and 24 hours after the administration.
Result(s): In the group treated with E2 mean concentration of NO metabolites 24 hours after patch application (37.31 +/- 7.62 mumol/L) resulted significantly higher than baseline (21.04 +/- 5.71 mumol/L) and the control group (23.50 +/- 4.03 mumol/L). The correlation between the mean percent increase in NO metabolites and absolute E2 concentrations 24 hours after the E2 administration was statistically significant.
Conclusion(s): Transdermal administration of E2 to healthy postmenopausal women increases the plasma levels of NO and this supports the hypothesis that a NO-related mechanisms may contribute to the cardiovascular protective effect of estrogens in postmenopause.