Retrograde and oscillatory shear increase across the menopause transition.

Yasina B Somani,Steriani Elavsky,Matthew A Barlow,David N Proctor,Joaquin U Gonzales,Danielle Jin-Kwang Kim,David J Moore

doi:10.14814/phy2.13965

Abstract

Declines in endothelial function can take place rapidly across the menopause transition, placing women at heightened risk for atherosclerosis. Disturbed patterns of conduit artery shear, characterized by greater oscillatory and retrograde shear, are associated with endothelial dysfunction but have yet to be described across menopause. Healthy women, who were not on hormone therapy or contraceptives, were classified into early perimenopausal, late perimenopausal, and early postmenopausal stage. Resting antegrade, retrograde, and oscillatory shear were calculated from blood velocity and diameter measured in the brachial and common femoral artery using Doppler ultrasound. Serum was collected for measurements of estradiol, follicle‐stimulating hormone (FSH), and luteinizing hormone. After adjusting for age, brachial artery oscillatory shear was significantly higher in early postmenopausal women (n = 15, 0.17 ± 0.08 a.u.) than both early (n = 12, 0.08 ± 0.05 a.u., P < 0.05) and late (n = 8, 0.08 ± 0.04 a.u) perimenopausal women, and retrograde shear was significantly greater in early postmenopausal versus early perimenopausal women (−19.47 ± 12.97 vs. −9.62 ± 6.11 sec−1, both P < 0.05). Femoral artery oscillatory and retrograde shear were greater, respectively, in early postmenopausal women (n = 15, 0.19 ± 0.08 a.u.; −13.57 ± 5.82 sec−1) than early perimenopausal women (n = 14, 0.11 ± 0.08 a.u.; −8.13 ± 4.43 sec−1, P < 0.05). Further, Pearson correlation analyses revealed significant associations between FSH and both retrograde and oscillatory shear, respectively, in the brachial (r = −0.40, P = 0.03; r = 0.43, P = 0.02) and common femoral artery (r = −0.45, P = 0.01; r = 0.56, P = 0.001). These results suggest menopause, and its associated changes in reproductive hormones, adversely influences conduit arterial shear rate patterns to greater oscillatory and retrograde shear rates.

Highlights

Patterns of arterial shear stress, the frictional force exerted by blood flow, are integral in the maintenance of vascular health (Malek et al 1999)
Of the total 37 women who participated in vascular assessments, 30 women had measures that were included in both brachial artery and femoral artery analysis
With respect to reproductive hormones, plasma concentrations of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) were significantly lower, and estradiol was higher in early perimenopausal women than in late perimenopausal and early postmenopausal women (P < 0.05)

Summary

Introduction

Patterns of arterial shear stress, the frictional force exerted by blood flow, are integral in the maintenance of vascular health (Malek et al 1999). High steady laminar flow induces intracellular calcium release stimulating endothelial release of vasodilators that inhibit blood coagulation, smooth muscle proliferation, and adhesion of molecules to the endothelial surface (Traub and Berk 1998). Highly oscillatory flow that includes a large retrograde (backward) component fails to increase intracellular calcium transients (Helmlinger et al 1995), providing a weak stimulus for endothelial release of vasoactive substances (Ziegler et al 1998). Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society.

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