Dopamine effects on neuromuscular function in hyperthermia

我们实验室的主要研究重点是人体在极端温度下的功能。在这个领域，一个重要的问题是，为什么与凉爽的条件相比，人类不能在炎热的条件下进行同样艰苦或同样长时间的锻炼。从历史上看，这方面的主要观点被认为是通过出汗来损失液体，使心脏工作更卖力。然而，在过去的二十年里，许多其他的新想法被提出和证明，包括我们的实验室表明，即使皮肤或肌肉本身保持凉爽，炽热的大脑招募和激活肌肉的能力也较弱。自那以后，我们通过观察大脑血液流动或脑血液化学如何影响肌肉功能来进一步研究这一点，这两项都可能随着体温的升高而改变。*其他实验室已经表明，大脑中的一种递质分子多巴胺水平较高，似乎会增加精神唤醒和身体的热量损失反应，可以导致健康的运动员在高温下锻炼更长时间和更努力，还能耐受更高的体温。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根据个人健康水平的不同而对其产生不同的影响。*我们的提案测试了多巴胺水平是否直接影响有氧体能高和低的人在高温下的肌肉功能，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.