BLOOD VOLUME AND VENOUS RETURN IN THERMAL STRAIN

该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，在人类中， 循环和热应变的条件。 具体目标是联系 皮肤血管张力和静脉张力的变化与动脉张力的变化 和中心静脉压的变化 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， 身体负压、颈部吸引和面部浸入冰水中。 在不同的环境温度和血液体积 在实验前被操纵过 另一个具体目标是 一个项目是检查决定毛细血管的Starling力 不适合、适合和热适应的人类受试者的滤过动力学， 为了确定有助于相对的生理变化， 在后一种情况下的高心脏充盈压，从而提供 抵抗晕厥和其他与热有关的疾病。 的另一个目的 本课题研究噻嗪类利尿剂对血液的影响， 随着时间的推移，最终目标是确定是否 对利尿剂使用的生理适应模仿了 对利尿剂使用的适应模仿了对听觉的生理适应， 运动暴露。 该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 由于使用噻嗪或β-肾上腺素能阻滞剂， 毒品 这对确定这些限制具有很大的实用价值。 人们锻炼和热暴露。 最后一个目标是研究 这些同样的规则在那些做过心脏移植的人身上， 因此心脏没有神经支配也没有低压压力感受器反射 能力。 这一研究不仅具有现实意义， 低压和高压压力感受器反射的分离， 进一步了解循环的控制。

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.