Johansen L B, Bie P, Warberg J, Christensen N J, Norsk P
Danish Aerospace Medical Centre of Research, Rigshospitalet, Copenhagen, Denmark.
Am J Physiol. 1995 Nov;269(5 Pt 2):R1068-76. doi: 10.1152/ajpregu.1995.269.5.R1068.
The present experiments were designed to elucidate 1) the role of the lower extremity capillary bed in decreasing plasma colloid osmotic pressure (COP) during immersion of humans (n = 8) for 6 h, and 2) the extent to which the natriuresis of water immersion is triggered by this decrease in COP. Irrespective of the depth, COPs were very similar during the immersion procedures, varying between 25.3 +/- 0.5 and 26.4 +/- 0.6 mmHg, which was significantly lower than during control (28.3 +/- 0.3 and 28.6 +/- 0.3 mmHg). During neck immersion, central venous pressure rose instantly by approximately 12 mmHg (P < 0.05) and remained elevated. Only a transient, marginal increase (1.6 +/- 0.7 mmHg) occurred during hip immersion. Cumulated sodium excretion during seated control, hip immersion, and neck immersion, respectively, differed significantly (30 +/- 5, 45 +/- 5, and 101 +/- 6 mmol). It is concluded that the decrease in COP during immersion is primarily due to fluid shifts occurring in the capillary bed of the legs and that this may account for up to 25% of the immersion-induced increase in renal sodium excretion.
1）在8名受试者浸入水中6小时的过程中，下肢毛细血管床在降低血浆胶体渗透压（COP）方面的作用；2）COP的降低引发水浸利尿的程度。无论浸入深度如何，在浸入过程中COP非常相似，在25.3±0.5至26.4±0.6 mmHg之间变化，显著低于对照期间（28.3±0.3和28.6±0.3 mmHg）。在颈部浸入期间，中心静脉压立即升高约12 mmHg（P<0.05）并持续升高。在臀部浸入期间仅出现短暂的、轻微的升高（1.6±0.7 mmHg）。坐位对照、臀部浸入和颈部浸入期间的累积钠排泄量分别有显著差异（30±5、45±5和101±6 mmol）。得出的结论是，浸入过程中COP的降低主要是由于腿部毛细血管床中发生的液体转移，这可能占浸入诱导的肾钠排泄增加量的25%。
