# Characterizing Sympathetic Neurovascular Transduction in Humans

 Title: Characterizing Sympathetic Neurovascular Transduction in Humans Author: Tan, Can Ozan; Tamisier, Renaud; Hamner, J. W.; Taylor, John Andrew Note: Order does not necessarily reflect citation order of authors. Citation: Tan, Can Ozan, Renaud Tamisier, J. W. Hamner, and J. Andrew Taylor. 2013. Characterizing sympathetic neurovascular transduction in humans. PLoS ONE 8(1): e53769. Full Text & Related Files: 3542370.pdf (468.4Kb; PDF) Abstract: Despite its critical role for cardiovascular homeostasis in humans, only a few studies have directly probed the transduction of sympathetic nerve activity to regional vascular responses – sympathetic neurovascular transduction. Those that have variably relied on either vascular resistance or vascular conductance to quantify the responses. However, it remains unclear which approach would better reflect the physiology. We assessed the utility of both of these as well as an alternative approach in 21 healthy men. We recorded arterial pressure (Finapres), peroneal sympathetic nerve activity (microneurography), and popliteal blood flow (Doppler) during isometric handgrip exercise to fatigue. We quantified and compared transduction via the relation of sympathetic activity to resistance and to conductance and via an adaptation of Poiseuille’s relation including pressure, sympathetic activity, and flow. The average relationship between sympathetic activity and resistance (or conductance) was good when assessed over 30-second averages (mean R$$^2$$=0.49±0.07) but lesser when incorporating beat-by-beat time lags (R$$^2$$=0.37±0.06). However, in a third of the subjects, these relations provided relatively weak estimates (R$$^2$$<0.33). In contrast, the Poiseuille relation reflected vascular responses more accurately (R$$^2$$=0.77±0.03, >0.50 in 20 of 21 individuals), and provided reproducible estimates of transduction. The gain derived from the relation of resistance (but not conductance) was inversely related to transduction (R$$^2$$=0.37, p<0.05), but with a proportional bias. Thus, vascular resistance and conductance may not always be reliable surrogates for regional sympathetic neurovascular transduction, and assessment from a Poiseuille relation between pressure, sympathetic nerve activity, and flow may provide a better foundation to further explore differences in transduction in humans. Published Version: doi:10.1371/journal.pone.0053769 Other Sources: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3542370/pdf/ Terms of Use: This article is made available under the terms and conditions applicable to Other Posted Material, as set forth at http://nrs.harvard.edu/urn-3:HUL.InstRepos:dash.current.terms-of-use#LAA Citable link to this page: http://nrs.harvard.edu/urn-3:HUL.InstRepos:10708065 Downloads of this work: