Effect of thermoregulatory function on relationship between cardiopulmonary baroreceptors and body fluid hemeostasis

本研究的主要目的是建立一个连续血容量和血浆电解质的测量系统。在接下来的步骤中，我们设计研究在以下条件下人类血浆量突然扰动期间血容量和电解质变化的机制。结合机械振荡器技术和离子电极法建立的测量系统，使我们能够在人体血流动力学扰动过程中精确、连续地测量血容量和血浆电解质。研究了3种不同水温浸泡时血管舒缩活性对血浆体积变化的影响；最大血管收缩值为32，热中性值为34.5，最小血管收缩值为36。血液和血浆密度在浸泡的前20-25分钟迅速降低，随后在浸泡的其余时间逐渐降低。这些变化不受水温的影响，表明经毛细血管液体的体积变化不受血管舒缩活动的影响。在饮水后不久，血液稀释（血容量双相变化），血液浓度一致。这一现象的机制归因于最初血压升高引起的液体通过毛细血管壁向外移动，以及后来由于吸收后机制引起的液体向内移动。在下体负压（LBNP，-15和-30 mmHg，持续10分钟）后立即出现短暂的血密度降低，随后血浆体积急剧增加而不减少，表明血流重新分布。LBNP后-8 min出现经毛细血管液体移位，恢复20 min后恢复到原来的空间。总之，本研究证明，本研究的在线系统是阐明人体毛细血管壁瞬时和快速流体运动机制的有用工具。少

The primary purpose of this study was to establish a system for measuring continuos blood volume and plasma electrolytes. In the next step, we designed to study the mechanisms responsible for the change in blood volume and electrolytes during an abrupt perturbation plasma volume in the following conditions in humans.1. An establishment of the measuring systems in combination of teh mechanical osicillator technique and ion-electrode method enabled us to measure a precise and continuous measurement of blood volume and plasma electrolytes during a course of hemodynamic perturbation in humans.2. Effect of vasomotor activity on plasma volume change during immersion was studied in 3 different water temperatures ; 32ﾟC at maximum vasoconstriction, 34.5ﾟC,thermoneutral, and 36ﾟC at minimmum vasoconstriction. A rapid reduction of blood and plasma densities in the first 20-25 min of imersion followed by a gradual reduction during the rest period of immersion. These changes were independent of th … More e water temperatures, sugesting that the volume of the transcapillary fluid shift is not modified by the vasomotor activity.3. A consistent hemoconcentration has been observed shortly after water drinking followed by a hemodilution (a biphasic change in blood volume). The mechanisms for this phenomenon was attributed to the outward shift of the fluid across the capillary walls because of the initial rise of blood presure and a later inward shift due to the postabsorptive mechanisms.4. A transient lowering of blood density immediately after lower body negative pressure (LBNP,-15 and -30 mmHg, for 10min) followed by a steep increase without reduction in plasma volume, indicating a redistribution of blood flow. The transcapillary fluid shift occurred -8 min after LBNP and returned to the original space in 20 during recovery.In conslusion, the present study proves that the on-line system of the present study is a useful tool for elucidate the mechanisms underlyting the transient and rapid fluid movement across the capilary walls in humans. Less