Cardiovascular Research Laboratory, Spaulding Rehabilitation Hospital, Boston, Massachusetts, United States of America.
PLoS One. 2013;8(1):e53769. doi: 10.1371/journal.pone.0053769. Epub 2013 Jan 10.
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.
尽管交感神经活动向区域性血管反应的传递（交感神经血管传递）在人类心血管稳态中起着至关重要的作用，但仅有少数研究直接探查了这一过程。这些研究依赖于血管阻力或血管传导性来量化反应。然而，目前尚不清楚哪种方法能更好地反映生理学。我们在 21 名健康男性中评估了这两种方法以及另一种方法的效用。我们在进行等长握力运动至疲劳的过程中记录了动脉血压（Finapres）、腓肠神经传出神经活动（微神经记录）和腘动脉血流（多普勒）。我们通过交感神经活动与阻力和传导性的关系以及包括压力、交感神经活动和血流的泊肃叶关系的一种适应性来量化和比较传递。当使用 30 秒平均值评估时，交感神经活动与阻力（或传导性）之间的平均关系良好（平均 R²=0.49±0.07），但当包含逐拍时间滞后时则较差（R²=0.37±0.06）。然而，在三分之一的受试者中，这些关系提供了相对较弱的估计值（R²<0.33）。相比之下，泊肃叶关系更准确地反映了血管反应（R²=0.77±0.03，21 人中的 20 人>0.50），并提供了传递的可重复估计值。阻力（但不是传导性）关系的增益与传递呈反比（R²=0.37，p<0.05），但具有比例偏差。因此，血管阻力和传导性可能并不总是区域性交感神经血管传递的可靠替代物，而从压力、交感神经活动和血流之间的泊肃叶关系进行评估可能为进一步探索人类传递中的差异提供更好的基础。
