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. Author manuscript; available in PMC: 2013 Jul 1.
Published in final edited form as: Acta Physiol (Oxf). 2012 Feb 18;205(3):372–380. doi: 10.1111/j.1748-1716.2012.02416.x

Figure 2.

Figure 2

Percent change (Δ) in vascular resistance index in the arm (left panels) and leg (right panels) of young (n=5) and older adults (n=5) in response to limb dependency. Data obtained before (Pre) and during systemic sympathetic blockade (Post) are presented on both an individual (open symbols) as well as mean basis (closed symbols; mean±SE). Indices of vascular resistance were calculated as mean arterial pressure/mean blood velocity (limb) or flux (skin). Responses are presented as the percent change in vascular resistance index from the baseline (limb at heart level) to the dependent position (limb lowered 30 cm below heart level). Mean arterial pressure was corrected to account for the hydrostatic pressure gradient created when the limb was studied in the dependent position (mean arterial pressure in control limb at heart level + 0.766 * 30 cm). Responses to limb dependency were not altered by sympathetic blockade in young or older adults. Limb VR in the arm was assessed in the brachial artery and in the leg in the popliteal artery. Skin VR in was assessed on the ventral aspect of the forearm (arm) and calf (leg).