Urinary excretion of vasoactive markers following estrogen replacement therapy in postmenopausal women

Objective: The effect of estradiol on the renal excretion of vasoactive sub stances was studied in postmenopausal women. The following markers surrogat ing an estrogenic effect on the cardiovascular system were measured: prosta cyclin and thromboxane, cGMP, which reflects systemic nitric monoxide produ ction, serotonin and relaxin. Methods: The effect of estradiol was compared using two clinical forms of administration, transdermal and oral, in two g roups of 20 postmenopausal women each. The treatment was carried out for tw o and four weeks, respectively. Nocturnal urine was collected over 8 hours before and after estradiol treatment. The quantity of markers excreted duri ng the experiment was determined. Results: Excretion of prostacyclin and th romboxane, calculated as prostacyclin/thromboxane ratio, was increased usin g both forms of administration. Both forms of treatment brought about only slight non-significant changes in renal cGMP excretion compared with values before treatment. The production of serotonin and relaxin was only increas ed using transdermal treatment. Conclusion: The resulting data show that es tradiol replacement in postmenopausal women is able to increase renal excre tion of various vasoactive substances implying a vasodilative effect of est rogen. This was seen, both in transdermal and oral administration, transder mal application having a more pronounced effect on the markers than oral ad ministration.