Department of Kinesiology, The University of Alabama, Tuscaloosa, AL 35487, USA.
Exp Physiol. 2011 Feb;96(2):163-70. doi: 10.1113/expphysiol.2010.055434. Epub 2010 Nov 1.
The ability to increase skin blood flow (SkBF) rapidly in response to local heating is diminished with advanced age; however, the mechanisms are unclear. The primary aim of this study was to investigate the role of sensory nerves in this age-related change. A secondary aim was to investigate the effect of aerobic fitness on sensory nerve-mediated vasodilatation in young and aged skin. We measured SkBF (using laser Doppler flowmetry) in young and older endurance-trained and untrained men (n= 7 in each group) at baseline and during 35 min of local skin heating to 42°C at two sites on the ventral forearm. One site was pretreated with topical anaesthetic cream to block local sensory nerve function. Cutaneous vascular conductance (CVC) was calculated as SkBF divided by mean arterial pressure and normalized to maximal values (CVC(max)) achieved during local heating to 44°C. At the untreated site, the rapid vasodilatation during the first ~5 min of local heating (initial peak) was lower in the older untrained group (68 ± 3%CVC(max)) compared with all other groups (young trained, 76 ± 4%CVC(max); young untrained, 75 ± 5%CVC(max); and older trained, 81 ± 3%CVC(max); P < 0.05). Sensory nerve blockade abolished these differences among the groups (P > 0.05). The contribution of sensory nerve-mediated vasodilatation was lower in the older untrained group compared with all other groups (P< 0.05). Our results suggest that the age-related decline in the rapid vasodilator response to local heating in human skin is explained by diminished sensory nerve-mediated vasodilatation. These findings also indicate that this age-related change can be prevented through participation in regular aerobic exercise.
皮肤血流量（SkBF）对局部加热的快速增加能力随着年龄的增长而减弱；然而，其机制尚不清楚。本研究的主要目的是研究感觉神经在这种与年龄相关的变化中的作用。次要目的是研究有氧健身对年轻和老年皮肤感觉神经介导的血管舒张的影响。我们在年轻和老年耐力训练和未训练男性（每组 7 人）的前臂腹侧两个部位测量了 SkBF（使用激光多普勒血流仪），在基线时和局部皮肤加热至 42°C 35 分钟期间。一个部位用局部麻醉乳膏预处理以阻断局部感觉神经功能。皮肤血管传导率（CVC）定义为 SkBF 除以平均动脉压，并归一化为局部加热至 44°C 时达到的最大值（CVC(max))。在未处理的部位，在局部加热的最初 5 分钟内（初始峰值），局部未训练的老年组的快速血管扩张（68±3%CVC(max))低于所有其他组（年轻训练组，76±4%CVC(max))；年轻未训练组，75±5%CVC(max))和老年训练组，81±3%CVC(max))；P<0.05)。感觉神经阻断消除了这些组之间的差异（P>0.05)。与所有其他组相比，局部未训练的老年组的感觉神经介导的血管扩张贡献较低（P<0.05)。我们的结果表明，人类皮肤对局部加热的快速血管扩张反应随年龄的增长而下降，这是由于感觉神经介导的血管扩张减弱所致。这些发现还表明，这种与年龄相关的变化可以通过定期进行有氧运动来预防。
