HEAT EXPOSURE, DEHYDRATION AND FEVER

适当和协调的生理调节不断发生，以 维持身体的动态平衡。这些活动涉及多个 监管系统，相互作用，以保持其最佳功能。而当 从概念上来说，实际上很少有研究检查过 系统地分析不同监管制度之间的相互关系 当两个或多个生理驱动同时发生时。作为 对不同驱动器的反应通常使用相同的效应器路径， 当将这些驱动器组合在一起时，可能会产生冲突 对身体施加同时的压力负荷，从而竞争 在同一时间，同样的机制。这就提出了一个问题：哪一个 当相互竞争的需求被置于 共享机制？在身体方面出现了一个特殊的两难境地 温度控制，因为温度调节系统不具备 它自己的效应器，而不是依赖于其他系统的效应器，例如， 循环、呼吸等，这也可能是 同时防御其他变量。一个例子中的情况 可能出现这种冲突的是当暴露在高温下，脱水和 感染是同时发生的。此外，这些压力源在一定程度上要求 常见效应器机构的相反反应。未能充分 满足需求可能会导致失代偿，例如 高温会导致中暑。但是在这样的条件下， 灾难性的结果通常是可以避免的：很明显，妥协是 达到了让身体能够应付的程度。这些建议的目的 因此，实验是为了更好地了解身体的位置 当它同时与其他竞争对手竞争时，温度调节 动态平衡系统。我们会给受过训练的清醒的兔子注射 致热剂量的内毒素，并在一系列实验中暴露 它们同时受到各种热负荷的影响。在接下来的系列中，我们将 此外，在这些治疗之前，将动物脱水1天。 我们将从根本上分析兔子的反应 每个调节系统的生理变量，即 体温调节，体温；对于感染，选择急性期 反应物；对于脱水，则为血浆渗透压。结果应该是 有助于我们理解动态平衡相互作用的本质， 在复杂情况下的生理调节的一般背景下。

Appropriate and coordinated physiological adjustments continually occur to maintain the body's homeostasis. These activities involve multiple regulatory systems, interacting to preserve their optimal function. While well understood conceptually, few studies have, in fact, examined systematically the interrelationships among different regulatory systems when two or more physiological drives occur simultaneously. As the responses to different drives often utilize the same effector pathways, a potential for conflict is created when these drives are combined and impose concurrent stressful loads on the body, thereby competing for the same mechanisms at the same time. This raises the question: which homeostatic response has priority when competing demands are placed on shared mechanisms? A particular dilemma occurs with regard to body temperature control because the thermoregulatory system does not possess its own effectors, but rather depends on those of other systems, e.g., circulatory, respiratory, etc., which may also be required in the simultaneous defense of other variables. An example of a situation in which such a conflict may arise is when heat exposure, dehydration and infection occur together. These stressors, moreover, call, in part, for opposite responses by common effector mechanisms. Failure to adequately meet the needs could result in decompensation, e.g., dehydration in the heat leads to heat exhaustion. However, under such conditions, catastrophic out-comes usually are averted: compromises are evidently reached that allow the body to cope. The purpose of these proposed experiments, therefore, is to better understand the place of body temperature regulation when it is in competition with other, simultaneous homeostatic systems. We will inject trained, conscious rabbits with pyrogenic doses of an endotoxin, and in one series of experiments, expose them concurrently to various heat loads. In a subsequent series, we will additionally dehydrate the animals for 1 day prior to these treatments. We will analyze the rabbits' responses in terms of the fundamental physiological variable of each regulated system, i.e., for thermoregulation, body temperature; for infection, selected acute-phase reactants; and for dehydration, plasma osmolality. The results should contribute to our understanding of the nature of homeostatic interactions, in the general context of physiological regulation in complex situations.