Engelland Rachel E, Hemingway Holden W, Tomasco Olivia G, Olivencia-Yurvati Albert H, Romero Steven A
Human Vascular Physiology Laboratory, Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, TX, USA.
Department of Surgery, University of North Texas Health Science Center, Fort Worth, TX, USA.
Exp Physiol. 2020 Feb;105(2):302-311. doi: 10.1113/EP088154. Epub 2019 Dec 11.
• What is the central question of this study? What is the effect of lower leg hot water immersion on vascular ischaemia-reperfusion injury induced in the arm of young healthy humans? • What is the main finding and its importance? Lower leg hot water immersion successfully protects against vascular ischaemia-reperfusion injury in humans. This raises the possibility that targeted heating of the lower legs may be an alternative therapeutic approach to whole-body heating that is equally efficacious at protecting against vascular ischaemia-reperfusion injury.
Reperfusion that follows a period of ischaemia paradoxically reduces vasodilator function in humans and contributes to the tissue damage associated with an ischaemic event. Acute whole-body hot water immersion protects against vascular ischaemia-reperfusion (I-R) injury in young healthy humans. However, the effect of acute lower leg heating on I-R injury is unclear. Therefore, the purpose of this study was to test the hypothesis that, compared with thermoneutral control immersion, acute lower leg hot water immersion would prevent the decrease in macro- and microvascular dilator functions following I-R injury in young healthy humans. Ten young healthy subjects (5 female) immersed their lower legs into a circulated water bath for 60 min under two randomized conditions: (1) thermoneutral control immersion (∼33°C) and (2) hot water immersion (∼42°C). Macrovascular (brachial artery flow-mediated dilatation) and microvascular (forearm reactive hyperaemia) dilator functions were assessed using Doppler ultrasound at three time points: (1) pre-immersion, (2) 60 min post-immersion, and (3) post-I/R (20 min of arm ischaemia followed by 20 min of reperfusion). Ischaemia-reperfusion injury reduced macrovascular dilator function following control immersion (pre-immersion 6.0 ± 2.1% vs. post-I/R 3.6 ± 2.1%; P < 0.05), but was well-maintained with prior hot water immersion (pre-immersion 5.8 ± 2.1% vs. post-I/R 5.3 ± 2.1%; P = 0.8). Microvascular dilator function did not differ between conditions or across time. Taken together, acute lower leg hot water immersion prevents the decrease in macrovascular dilator function that occurs following I-R injury in young healthy humans.
• 本研究的核心问题是什么？小腿热水浸泡对年轻健康人手臂诱导的血管缺血再灌注损伤有何影响？
• 主要发现及其重要性是什么？小腿热水浸泡成功地保护人体免受血管缺血再灌注损伤。这增加了一种可能性，即针对性地加热小腿可能是全身加热的一种替代治疗方法，在预防血管缺血再灌注损伤方面同样有效。
缺血一段时间后的再灌注反常地降低了人体的血管舒张功能，并导致与缺血事件相关的组织损伤。急性全身热水浸泡可保护年轻健康人免受血管缺血再灌注（I-R）损伤。然而，急性小腿加热对I-R损伤的影响尚不清楚。因此，本研究的目的是检验以下假设：与体温中性对照浸泡相比，急性小腿热水浸泡可预防年轻健康人I-R损伤后大、微血管舒张功能的下降。10名年轻健康受试者（5名女性）在两种随机条件下将小腿浸入循环水浴中60分钟：（1）体温中性对照浸泡（约33°C）和（2）热水浸泡（约42°C）。在三个时间点使用多普勒超声评估大血管（肱动脉血流介导的扩张）和微血管（前臂反应性充血）舒张功能：（1）浸泡前，（2）浸泡后60分钟，以及（3）I/R后（手臂缺血20分钟，然后再灌注20分钟）。缺血再灌注损伤在对照浸泡后降低了大血管舒张功能（浸泡前6.0±2.1% vs. I/R后3.6±2.1%；P<0.05），但在先前热水浸泡后得到了良好维持（浸泡前5.8±2.1% vs. I/R后5.3±2.1%；P = 0.8）。条件之间或不同时间的微血管舒张功能没有差异。综上所述，急性小腿热水浸泡可预防年轻健康人I-R损伤后发生的大血管舒张功能下降。
