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

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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