The vascular endothelium is a single layer of cells lining all the blood vessels in the body. The endothelium is essential for vasodilatation in response to increases in blood flow associated shear stress: termed endothelium dependent flow mediated vasodilatation (FMD).
Several vasodilators are released by the endothelium in response to shear stress including nitric oxide and prostacyclin. A small FMD response is interpreted as indicating a low nitric oxide bioavailability and is associated with an increased risk of vascular disease and cardiac events.
Vascular endothelial and smooth muscle cells express estrogen receptors A and B.
The study indicated below, evaluated flow mediated dilatation (FMD) of the brachial artery in 134 postmenopausal women before and after acute (1 hour) and chronic (3 months) of estrogen administration (replacement).
Estrogen administration improved FMD more in women within five years of menopause, (76% acute, 74% chronic administration) than in women more than five years since menopause (45% acute, 48% chronic).
Although acute and chronic estrogen administration improved endothelial function in all women, the improvement was dependent on time since menopause: the duration of hormone deprivation.
Women who had previously used estrogen replacement also had more improved FMD (59% acute, 63% chronic) upon administration than nonusers of estrogen replacement (31% acute, 38% chronic).
Estrogen tends to exert a favorable effect on endothelial function and arterial health when estrogen replacement therapy (ERT) or HRT is initiated soon after menopause.
Keep in mind, the type/dose, time of initiation of ERT or HRT should be customized to a woman’s age, cardiovascular risk factors and pre-existing cardiovascular conditions.
Source:
Time Since Menopause Influences the Acute and Chronic Effect of Estrogens on Endothelial Function. Cristiana Vitale, Giuseppe Mercuro MD’s
Arteriosclerosis, Thrombosis and Vascular Biology. 2008;28:348
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