We sought to determine how whole-body heating acutely influences radial artery function, characterized using flow mediated dilation (FMD) and low-flow mediated constriction (L-FMC), and the mechanistic role of shear rate modification on radial artery functional characteristics during heating. Eleven young healthy men underwent whole-body heating (water-perfused suit) sufficient to raise core temperature +1°C. Trials were repeated with (Heat+WC) and without (Heat) the application of a wrist cuff located distal to the radial artery examined, known to prevent increases in mean and anterograde shear rate but increase retrograde shear. Radial artery characteristics were assessed throughout each trial, with FMD and L-FMC assessed prior to and upon reaching the target core temperature. Heat markedly increased radial artery mean and anterograde shear rate, along with radial artery diameter and blood flow (P<0.05). Heat+WC abolished the heat-induced increase mean and anterograde shear rate (P>0.05), but markedly increased retrograde shear (P<0.05). Concomitantly, increases in radial artery diameter and blood flow were decreased (Heat+WC vs Heat,P<0.05). Heat attenuated FMD (8.6±1.2 vs. 2.2±1.4%, P<0.05), whereas no change in FMD was observed in Heat+WC (7.8±1.2 vs. 10.8±1.2%,P>0.05). In contrast, L-FMC was not different in either trial (P>0.05). In summary, acute whole-body heating markedly elevates radial artery shear rate, diameter and blood flow, and diminishes FMD. However, marked radial artery vasodilation and diminished FMD are absent when these shear rate changes are prevented. Shear rate modifications underpinthe radial artery response to acute whole-body heat-stress, but further endothelial-dependent vasodilation (FMD) is attenuated likely as the vasodilatory range limit is approached.

中文翻译：

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全身被动热应激和动脉剪切速率改变对年轻人radial动脉功能的影响

我们试图确定全身加热如何通过流介导的扩张（FMD）和低流介导的收缩（L-FMC）来表征急性加热的radial动脉功能，以及加热过程中剪切速率调节对artery动脉功能特征的机械作用。11名健康的年轻人接受了全身加热（注水服），足以使核心温度升高+ 1°C。在（Heat + WC）和不使用（Heat）的情况下，重复试验，检查位于examined动脉远端的腕带，以防止平均和顺行剪切速率增加，但增加逆行剪切。在每个试验中均评估动脉特征，并在达到目标核心温度之前和之后评估FMD和L-FMC。热量显着增加了radial动脉平均和顺向剪切速率，以及radial动脉直径和血流量（P <0.05）。Heat + WC消除了热诱导的平均剪切强度和顺向剪切速率（P> 0.05），但逆向剪切强度显着增加（P <0.05）。同时，radial动脉直径的增加和血流量的减少（Heat + WC vs Heat，P <0.05）。热衰减FMD（8.6±1.2对2.2±1.4％，P <0.05），而在Heat + WC中未观察到FMD的变化（7.8±1.2对10.8±1.2％，P> 0.05）。相反，在任一试验中，L-FMC均无差异（P> 0.05）。总之，急性全身加热显着提高了radial动脉的剪切速率，直径和血流量，并降低了FMD。然而，当这些剪切速率的变化被阻止时，就没有明显的radial动脉血管扩张和FMD减少。剪切速率的改变增强了radial动脉对急性全身热应激的反应，