Dm. Gilligan et al., EFFECTS OF ESTROGEN REPLACEMENT THERAPY ON PERIPHERAL VASOMOTOR FUNCTION IN POSTMENOPAUSAL WOMEN, The American journal of cardiology, 75(4), 1995, pp. 264-268
Hormone replacement therapy is associated with a reduction in cardiova
scular events in postmenopausal women. We have recently found that acu
te 17 beta-estradiol administration improves endothelium-dependent vas
odilation in both the peripheral and coronary circulations of postmeno
pausal women. The current study was undertaken in 33 estrogen-deficien
t postmenopausal women (mean age 59 +/- 7 years) to determine if short
term estrogen replacement therapy also improves endothelium-dependent
vasodilation in peripheral circulation. Acute intraarterial infusion
of estradiol, which increased forearm venous estradiol levels from 16
+/- 11 to 345 +/- 202 pg/ml, potentiated forearm vasodilation induced
by the endothelium-dependent vasodilator acetylcholine by 49 +/- 67% (
p <0.001). Acute estradiol also potentiated vasodilation induced by th
e endothelium-independent vasodilator nitroprusside by 5 +/- 31% (p =
0.04). However, after 3 weeks of transdermal estradiol administration
(0.1 mg/day), which achieved an estradiol level of 120 +/- 57 pg/ml, t
he vasodilator responses to acetylcholine and to sodium nitroprusside
were unchanged from initial measurements obtained before acute adminis
tration of estradiol, Repeat intraarterial infusion of estradiol in 8
women, while receiving transdermal estradiol, increased forearm venous
estradiol levels to 268 +/- 105 pg/ml and again potentiated the vasod
ilator response to acetylcholine to a similar degree as that observed
in the initial study after acute administration of estradiol. Thus, al
though acute intraarterial infusion of 17 beta-estradiol potentiates e
ndothelium-dependent vasodilation in the forearms of postmenopausal wo
men, this effect is not maintained with a 3-week cycle of systemic est
radiol administration. The different effects of acute and chronic estr
adiol may be due to the lower plasma levels achieved with chronic estr
ogen administration.