Nitric oxide synthase-dependent cutaneous vasodilation is regionally homogeneous despite inter-individual variability in post-menopausal females.

The objectives of this study were to 1) identify physiological and experimental factors associated with inter-individual variability in nitric oxide synthase (NOS)-dependent cutaneous vasodilation in post-menopausal females and 2) characterize regional variation in NOS-dependent vasodilation during local thermal hyperemia. Cutaneous vascular conductance (CVC), expressed as a percentage of maximum vasodilation (%CVCmax), was assessed at the chest, abdomen, forearm, and calf in 54 post-menopausal females using laser-Doppler flowmetry. Local skin temperature was raised from 33°C to 42°C for ~30 min, followed by an additional ~40 min of continued heating with infusion of 20 mM NG-nitro-L-arginine methyl ester (L-NAME; NOS inhibitor) via intradermal microdialysis. The NOS-dependent contribution to vasodilation was defined as the difference in %CVCmax between the 42°C and L-NAME plateaus. The measured participant characteristics of menopause duration, body fat percentage, peak oxygen uptake (V̇O2peak, or season of measurement were not associated with the NOS-dependent contribution to vasodilation, nor were any phase-specific measure of skin temperature, heart rate, or diastolic blood pressure. During heating to 42°C, menopause duration (years) was negatively associated with %CVCmax, while winter testing (December-March) was positively associated with %CVCmax ( both P ≤ 0.025). There were no significant regional differences in NOS-dependent vasodilation (all P ≥ 0.61). These findings demonstrate that NOS-dependent cutaneous vasodilation is regionally homogeneous in post-menopausal females despite inter-individual variability, and that physiological and environmental factors explain only a modest proportion of this variability, highlighting the need to identify additional regulators of cutaneous microvascular function in this population.