Effects of estradiol on measurements of conduit artery endothelial function after ischemia and reperfusion in premenopausal women

In premenopausal women ovarian steroids are felt to play a role in the prevention of cardiovascular disease. We aimed to assess whether menstrual cycle variations in estrogen can modify the response to ischemia/reperfusion (IR) injury in humans. In an investigator-blind crossover study in 10 healthy, pre-menopausal women with regular menstrual cycles. They had flow-mediated dilatation (FMD) measured by ultrasound in the radial artery before and after IR (15 minutes of brachial artery ischemia, 15 minutes of reperfusion) during both the early and late follicular phases of the menstrual cycle. The order of these visits was not randomized. IR significantly blunted FMD in the early follicular phase (pre-IR: 7.1±1.0%; post-IR: 3.6±1.0%, P=0.01) when estradiol levels were low (148.4±19.8 pmol/L). Conversely, FMD was preserved after IR during the late follicular phase (pre-IR: 7.2±0.9%; post-IR: 7.0±0.8%, P=NS, P=0.03 compared to early follicular) when estradiol levels were high (825.7±85.8 pmol/L, PThe accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author