Dopamine effects on neuromuscular function in hyperthermia

我们的实验室主要研究人体在极端温度下的功能。在这一领域，一个重要的问题是，为什么人类不能在炎热的环境中比在凉爽的环境中锻炼得更努力或更长时间。从历史上看，这一点的主要观点是通过出汗使心脏更努力地工作而流失液体。然而，在过去的20年里，人们提出并证明了许多其他的新想法，包括我们的实验室表明，即使皮肤或肌肉本身保持凉爽，热的大脑也不太能够招募和激活肌肉。后来，我们通过观察脑血流或脑血液化学物质如何影响肌肉功能来进一步研究这一点，这两种物质都可能会随着体温的升高而变化。其他实验室已经表明，大脑中的多巴胺是一种递质分子，似乎会增加精神唤醒，也会增加身体的热损失反应，可以使健康的运动员在高温下运动更长时间，更努力，也能忍受更高的体温。然而，我们不知道多巴胺在高温下如何影响肌肉功能。我们也不知道多巴胺是否会对不同健康水平的个体产生不同的影响。我们的提案测试了多巴胺水平是否会直接影响有氧健康水平高和有氧健康水平低的人在高体温下的肌肉功能，总体目标是更好地了解我们如何在高热应激的情况下保持体温。

Our lab has a main research focus on how the human body functions during extreme temperatures. In this field, an important question is why humans cannot exercise as hard or for as long in hot compared to cooler conditions. Historically, the main idea for this is suggested to be the loss of fluid through sweating making the heart work harder. However, many other new ideas have been proposed and demonstrated over the last twenty years, including our lab showing that a hot brain is less able to recruit and activate muscles, even if the skin or muscle itself is kept cool. We have since studied this further by looking at how brain blood flow or brain blood chemistry, both of which may change with high body temperatures, can affect muscle function.Other labs have shown that higher levels of dopamine, a transmitter molecule in the brain that seems to increase mental arousal and also heat loss responses in the body, can cause fit athletes to exercise longer and harder in the heat, and also be able to tolerate higher body temperatures. However, we do not know how dopamine might affect muscle function in the heat. We also do not know whether dopamine may affect individuals differently depending on their fitness levels.Our proposal tests whether dopamine levels directly affects muscle function at high body temperatures in people with both high and low aerobic fitness, with the overall goal of better understanding how we maintain body temperature in situations of high heat stress.