title: Cutaneous Mechanoreceptor Feedback from the Hand and Foot Can Modulate Muscle Sympathetic Nerve Activity.
abstract: Stimulation of high threshold mechanical nociceptors on the skin can modulate efferent sympathetic outflow. Whether low threshold mechanoreceptors from glabrous skin are similarly capable of modulating autonomic outflow is unclear. Therefore, the purpose of this study was to examine the effects of cutaneous afferent feedback from the hand palm and foot sole on efferent muscle sympathetic nerve activity (MSNA). Fifteen healthy young participants (9 male; 25 ± 3 years [range: 22-29]) underwent microneurographic recording of multi-unit MSNA from the right fibular nerve during 2 min of baseline and 2 min of mechanical vibration (150 Hz, 220 μm peak-to-peak) applied to the left hand or foot. Each participant completed three trials of both hand and foot stimulation, each separated by 5 min. MSNA burst frequency decreased similarly during the 2 min of both hand (20.8 ± 8.9 vs. 19.3 ± 8.6 bursts/minute [Δ -8%],p= 0.035) and foot (21.0 ± 8.3 vs. 19.5 ± 8.3 bursts/minute [Δ -8%],p= 0.048) vibration but did not alter normalized mean burst amplitude or area (Allp> 0.05). Larger reductions in burst frequency were observed during the first 10 s (onset) of both hand (20.8 ± 8.9 vs. 17.0 ± 10.4 [Δ -25%],p< 0.001) and foot (21.0 ± 8.3 vs. 18.3 ± 9.4 [Δ -16%],p= 0.035) vibration, in parallel with decreases in normalized mean burst amplitude (hand: 0.45 ± 0.06 vs. 0.36 ± 0.14% [Δ -19%],p= 0.03; foot: 0.47 ± 0.07 vs. 0.34 ± 0.19% [Δ -27%],p= 0.02) and normalized mean burst area (hand: 0.42 ± 0.05 vs. 0.32 ± 0.12% [Δ -25%],p= 0.003; foot: 0.47 ± 0.05 vs. 0.34 ± 0.16% [Δ -28%],p= 0.01). These results demonstrate that tactile feedback from the hands and feet can influence efferent sympathetic outflow to skeletal muscle.
authors.affiliation: Department of Human Health and Nutritional Science, University of Guelph Guelph, ON, Canada.
authors.forename: Nicholas D J
authors.initials: ND
authors.lastname: Strzalkowski
authors.affiliation: Department of Human Health and Nutritional Science, University of Guelph Guelph, ON, Canada.
authors.forename: Anthony V
authors.initials: AV
authors.lastname: Incognito
authors.affiliation: Department of Human Health and Nutritional Science, University of Guelph Guelph, ON, Canada.
authors.forename: Leah R
authors.initials: LR
authors.lastname: Bent
authors.affiliation: Department of Human Health and Nutritional Science, University of GuelphGuelph, ON, Canada; Toronto General Research Institute, Toronto General HospitalToronto, ON, Canada.
authors.forename: Philip J
authors.initials: PJ
authors.lastname: Millar
keywords: afferent feedback; autonomic nervous system; cutaneous; microneurography; muscle sympathetic neural activity; vibration