Sex and limb-specific ischemic reperfusion and vascular reactivity

Abstract

Nishiyama SK, Wray DW, Richardson RS. Sex and limbspecific ischemic reperfusion and vascular reactivity. Am J Physiol Heart Circ Physiol 295: H1100 -H1108, 2008. First published July 11, 2008 doi:10.1152/ajpheart.00318.2008.-With little known regarding sex and limb heterogeneity, we investigated vascular reactivity and ischemic reperfusion (IR) in the upper and lower extremities of 15 healthy men (26 Ϯ 2 yr) and women (23 Ϯ 1 yr). Doppler ultrasound was used to evaluate IR and flow-mediated dilation (FMD) after suprasystolic cuff occlusion in both the arm [brachial artery (BA)] and the leg [popliteal artery (PA)]. Cumulative IR [area under the curve (AUC)], normalized for muscle mass, revealed no sexrelated differences in either limb (forearm: men 38 Ϯ 3 and women 44 Ϯ 4 ml/100 g; lower leg: men 12 Ϯ 2 and women 14 Ϯ 2 ml/100 g), while both groups revealed a greater IR per unit of arm muscle mass (AUC) compared with the lower leg (P Ͻ 0. vasodilation; vascular function; hyperemia; females THE INCIDENCE OF CARDIOVASCULAR disease differs significantly between men and women. This is thought to be predominantly due to sex-specific differences in risk factors and the hormonal milieu. Indeed, epidemiologic studies have revealed that atherosclerosis, hypertension, and peripheral vascular and coronary artery diseases occur with greater prevalence in men and in postmenopausal women compared with premenopausal women (4, 23, 26), while clinical assessments of endotheliumdependent peripheral artery vasomotion, flow-mediated vasodilation (FMD), in healthy populations suggest that vascular function is superior in premenopausal women compared with their postmenopausal counterparts and with men (27, 40, 52). En masse, these studies have implicated estrogen as both a prostaglandin promoter and an antioxidant, protecting nitric oxide (NO) from degradation and facilitating increased vasomotion (29, 39). Thus current knowledge suggests that female sex hormones, such as estrogen, have positive vascular effects, whereas their absence could be related to vascular dysfunction and subsequent atherogenic disease states. However, in studies assessing FMD, when the initial value of arterial diameter is taken into consideration, vasodilation appears similar between males and females (18). This suggests that some of the documented sex differences in vascular reactivity could be the consequence of a mathematical bias rather than the beneficial effects of the female hormonal milieu.There is an emerging belief that vascular function in the arms and legs of humans is not uniform, but to our knowledge there is a relative paucity of studies that examine limb-specific sex differences in vascular reactivity. Most studies of arterial FMD have been conducted in the brachial artery (BA), but the extent to which this can index systemic vascular function has recently been questioned (35,54). Humans, as upright bipeds, are regularly subjected to large hydrostatic and transmural forces in the legs that appear to contribute to differential vasoreactivity (...

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Role of α1-adrenergic vasoconstriction in the regulation of skeletal muscle blood flow with advancing age

“…Indeed, it should be emphasized that a growing body of work from our group (8,(21)(22)(23)47) and others (18,19,24,31,42) has identified a limb specificity in vascular function, including responses to PE (25). Thus recognition that the present study was performed in the leg is essential for interpretation of the present findings and indeed may partially explain the disparity in responses between the present study and prior work in the exercising forearm (6,9).…”

Regulation of subcutaneous adipose tissue blood flow is related to measures of vascular and autonomic function

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