Abstract
While muscle sympathetic nerve activity (MSNA) is elevated with advancing age, correlational evidence suggests that, in contrast to men, basal MSNA is not related to resting lower limb hemodynamics in women. However, limited data exists in women that have attempted to directly assess the degree of limb sympathetic vasoconstrictor tone, and whether it is altered with age. To address this issue, we measured changes in femoral artery vascular conductance (FVC) during an acute sympatho‐inhibitory stimulus (−60 mm Hg neck suction, NS) in groups of healthy younger (n = 8, 23 ± 1 years) and older (n = 7, 66 ± 1 years) women. The percent change in FVC in response to NS was significantly augmented in the older (P = 0.006 vs. young) women. Although NS caused no significant change (3 ± 3%, P = 0.33) in FVC in the young women, there was a robust increase in FVC (21 ± 5%, P = 0.003) in the old women. Collectively, these findings provide evidence that in women, leg sympathetic vasoconstrictor tone emerges with age.
Highlights
Regulation of the skeletal muscle vasculature plays an important role in systemic blood pressure and metabolic homeostasis (Lind and Lithell 1993)
Muscle sympathetic nerve activity (MSNA; peroneal nerve) to the leg vasculature becomes elevated with a 2015 The Authors
The primary novel finding of the present study is that sympathetic vasoconstrictor tone of the lower limb is augmented in old compared with young women
Summary
Regulation of the skeletal muscle vasculature plays an important role in systemic blood pressure and metabolic homeostasis (Lind and Lithell 1993). Age-associated changes in the caliber of skeletal muscle resistance vessels in the lower limbs (Dinenno et al 1999, 2001a,b; Moreau et al 2003; Smith et al 2007) may contribute to the increased prevalence of metabolic and cardiovascular diseases in older adults (Lind and Lithell 1993). In contrast to findings in men, age-group differences in MSNA do not appear to explain attenuated leg blood flow and vascular conductance values observed in older women (Moreau et al 2003). Any potential age-group and/or inter-individual differences in either neural (e.g., adrenergic neurotransmitter release or vascular responsiveness) or non-neural (e.g., resistance vessel structure) factors could contribute to the lack of an observed association in women It remains unresolved whether aging influences leg sympathetic vasoconstrictor tone in women. We assessed leg (femoral artery) vascular conductance responses to acute sympathetic inhibition with carotid artery baroreceptor loading (À60 mm Hg neck suction) as a measure of whole-limb sympathetic vasoconstriction in groups of healthy younger and older women
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