Hodges Gary J, McGarr Gregory W, Mallette Matthew M, Del Pozzi Andrew T, Cheung Stephen S
Environmental Ergonomics Laboratory, Department of Kinesiology, Brock University, St. Catharines, ON L2S 3A1, Canada.
Integrative Exercise Physiology Laboratory, School of Kinesiology, Ball State University, Muncie, IN 47306, USA.
Microvasc Res. 2016 May;105:1-6. doi: 10.1016/j.mvr.2015.12.004. Epub 2015 Dec 8.
During local skin heating, the temporal onset of vasodilatation is delayed in the leg compared to the forearm, and sensory nerve blockade abolishes these differences. However, previous work using rapid skin heating did not allow for determination of sensory nerve influences on temperature thresholds for vasodilatation. Two sites were examined on both the forearm and leg, one control (CTRL), and one treated for sensory nerve blockade (EMLA). Skin blood flux was monitored using laser-Doppler probes, with heaters controlling local skin temperature (Tloc). Tloc was increased from 32-44 °C (+1 °C·10 min(-1)). Stimulus-response curves were constructed by fitting a four-parameter logistic function. EMLA significantly increased Tloc onset in the forearm (CTRL=35.3 ± 0.4 °C; EMLA=36.8 ± 0.7 °C) and leg (CTRL=36.5 ± 0.4 °C; EMLA=38.4 ± 0.5 °C; both P<0.05). At both CTRL and EMLA, Tloc onset was higher in the leg compared to the forearm (both P<0.05). In the forearm, median effective temperature to elicit 50% vasodilatation (ET50) was similar between sites (CTRL=39.7 ± 0.3 °C; EMLA=40.2 ± 0.4 °C; P=0.09); however, in the leg, EMLA significantly increased ET50 (CTRL=40.2 ± 0.3 °C; EMLA=41.0 ± 0.3 °C)(P<0.05). At CTRL sites, no limb difference was observed for ET50 (P=0.06); however, with EMLA, ET50 was significantly higher in the leg (P<0.05). EMLA significantly increased the gain of the slope at the forearm, (CTRL=0.31 ± 0.01%CVCmax·°C(-1); EMLA=0.45 ± 0.07%CVCmax·°C(-1)), and leg (CTRL=0.37 ± 0.05%CVCmax·°C(-1); EMLA=0.54 ± 0.04%CVCmax·°C(-1))(both P<0.05). At CTRL sites, the gain was significantly higher in the leg (P<0.05); however, for EMLA, no significant limb difference existed (P=0.10). These data indicate that the onset of vasodilatation occurs at a lower temperature in the forearm than the legs, and sensory nerves play an important role in both limbs.
在局部皮肤加热过程中，与前臂相比，腿部血管舒张的时间延迟，而感觉神经阻滞可消除这些差异。然而，以往使用快速皮肤加热的研究无法确定感觉神经对血管舒张温度阈值的影响。在前臂和腿部均检查了两个部位，一个为对照部位（CTRL），另一个进行了感觉神经阻滞处理（EMLA）。使用激光多普勒探头监测皮肤血流量，通过加热器控制局部皮肤温度（Tloc）。Tloc从32℃升至44℃（升温速率为1℃·10分钟⁻¹）。通过拟合四参数逻辑函数构建刺激 - 反应曲线。EMLA显著提高了前臂（CTRL = 35.3±0.4℃；EMLA = 36.8±0.7℃）和腿部（CTRL = 36.5±0.4℃；EMLA = 38.4±0.5℃；P均<0.05）的Tloc起始温度。在CTRL和EMLA组中，腿部的Tloc起始温度均高于前臂（P均<0.05）。在前臂，两个部位引起50%血管舒张的中位有效温度（ET50）相似（CTRL = 39.7±0.3℃；EMLA = 40.2±0.4℃；P = 0.09）；然而，在腿部，EMLA显著提高了ET50（CTRL = 40.2±0.3℃；EMLA = 41.0±0.3℃）（P<0.05）。在CTRL部位未观察到ET50的肢体差异（P = 0.06）；然而，使用EMLA时，腿部的ET50显著更高（P<0.05）。EMLA显著增加了前臂（CTRL = 0.31±0.01%CVCmax·℃⁻¹；EMLA = 0.45±0.07%CVCmax·℃⁻¹）和腿部（CTRL = 0.37±0.05%CVCmax·℃⁻¹；EMLA = 0.54±0.04%CVCmax·℃⁻¹）斜率增益（P均<0.05）。在CTRL部位，腿部的增益显著更高（P<0.05）；然而对于EMLA，不存在显著肢体差异（P = 0.10）。这些数据表明，前臂血管舒张的起始温度低于腿部，且感觉神经在两个肢体中均起重要作用。
