BLOOD VOLUME AND VENOUS RETURN IN THERMAL STRAIN

这个项目的长期目标是提供一个更完整的 了解有助于维持适当的 静脉回流，因此心脏充盈压，在人类 循环和热应变的条件。具体的目标是联系 皮肤血管运动和毒液运动张力随动脉变化的变化 受试者在高负荷状态下的中心静脉压 循环和热量需求。这将通过以下方式实现 受试者在高温下锻炼，并将休息的受试者暴露在较低的温度下 冰水中的身体负压、颈部吸力和面部浸泡 不同的环境温度和在血液容量具有 在实验前被操控过。的另一个具体目标是 该项目是研究决定毛细管的斯塔林力 不适合、适合和热习服人体的滤过动力学 以确定有助于相对 在后一种情况下心脏充盈压较高，从而提供 抵抗晕厥和其他与高温相关的疾病。另一个目的是 本课题旨在研究噻嗪类利尿剂对血液的影响。 随着时间的推移，体积，最终目标是确定 对利尿剂使用的生理性适应模仿生理学 利尿剂的使用模拟了听和听的生理适应 运动暴露。这个项目的另一个目标是评估 轻度高血压患者的体温和循环调节 因使用噻嗪或β-肾上腺素能受体阻滞剂而得到控制 毒品。这对于确定这些限制具有很大的实用价值 人们有锻炼和高温暴露的习惯。最终目标是研究 同样的规定也适用于接受过心脏移植和 因此，心脏没有神经支配，没有低压压力感受器反射 能力。这样的研究除了具有实际意义外，还可以让 低压和高压压力反射的分离，因此和能力 对循环控制有进一步的了解。

The long-term objectives of this project are to provide a more complete understanding of the factors contributing to the maintenance of an adequate venous return, and therefore cardiac filling pressure, in humans in conditions of circulatory and thermal strain. Specific aims are to relate changes in cutaneous vasomotor and venomotor tone to changes in arterial and central venous pressure in human subjects during conditions of high circulatory and thermal demand. This will be accomplished by having subjects exercise in the heat and by exposing resting subjects to lower body negative pressure, neck suction and facial immersion in ice water at different ambient temperatures and in condition in which blood volume has been manipulated prior to the experiment. Another specific aim of the project is to examine the Starling forces that determine capillary filtration dynamics in unfit, fit and heat acclimatized human subjects in order to identify the physiological changes that contribute to a relatively high cardiac filling pressure in the latter conditions and thereby provide resistance to syncope and other heat-related disorders. Another aim of present project is to study the effects of thiazide diuretics on blood volume over time, with the ultimate objective of determining whether the physiological adaptations to diuretic use mimic the physiological adpatations to diuretic use mimic the physiological adaptations to hear and exercise exposure. Another objective of this project is to evaluate the thermal and circulatory regulations in mild hypertensive individuals who are under control due to use of thiazide or Beta-adrenergic blocking drugs. This has great practical value in determining what limiations these people have for exercise and heat exposure. A final goal is the study of these same regulations in people who have had heart transplants and therefore no innervation to the heart and no low pressure baroreflex capability. Besides having practical significance, such study allows the separation of low from high pressure baroreflexes and thus and ability to gain further understanding of the control of the circulation.