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

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.