Impact of estradiol blood concentrations on skin capillary Laser Doppler flow in premenopausal women

Objective and method: Estradiols are known to prevent cardiovascular diseas es, but the underlying mechanisms remain unclear. We assessed the finger sk in capillary blood flow in 20 premenopausal women with oral contraception n oninvasively by Laser Doppler flowmetry (LDF). Blood flow was registered bo th under basal conditions and after 2 min of arterial occlusion. Furthermor e, the combination with a beat-to-beat online finger blood pressure monitor allowed the calculation of the regional peripheral resistance (RPR). All m easurements: were performed in the menstrual phase. LDF and RPR were correl ated to the estradiol whole blood levels. Results: Both baseline (r(2) = 0. 826; P<0.01) and vasodilation (r(2) =0.747; P<0.01) blood flux were signifi cantly correlated to the corresponding estradiol concentrations. a multiple stepwise regression analysis (with age, height, weight, duration of oral c ontraception, nicotine pack years and estradiol levels in the equation) sho wed positive correlations between estradiol levels and (a) baseline (P<0.05 ) or (b) vasodilation (P<0.05) Laser Doppler flux or (c) time to reach the peak flux (r(2) = 0.31; P<0.05). Furthermore, the minimal local vascular re sistance was negatively correlated to the estradiol levels (r(2)=0.45; P<0. 05). Conclusion: The study provides evidence that both the baseline and the vasodilation capillary blood flux in women in the menstrual phase depend o n the estradiol whole blood levels. Furthermore, the local vascular resista nce shows a negative correlation to the hormonal state. Functional or struc tural alterations of the microvasculature may therefore contribute to the e stradiol-associated cardiovascular protection. (C) 2000 Elsevier Science Ir eland Ltd. All rights reserved.