Relationship between exercise-induced hypervolemia and albumin synthesis and distribution in the body

[背景]众所周知，运动训练是增加血容量（BV）的有效刺激，这是由许多因素决定的，如肾脏水和Na^+的处理以及细胞和细胞外空间之间的液体运动。然而，运动训练导致BV增加的机制中涉及的因素尚不清楚。[目的]1。跑步机运动可增加大鼠的BV，大鼠可作为研究BV增加机制的模型动物。维持血浆肿瘤压的主要物质白蛋白可能是BV升高的一个因素吗？[方法]将大鼠分为运动训练组和不训练组（Ex组和Con组，每组n=10）。对照组在23℃正常笼中饲养，ld12:12 h。Ex组在相同条件下饲养，但进行1 h的跑步机运动，为期4周（5天/周）。跑步机速度设定为10 m/sec，坡度每周从0°增加到15°。第3周末，在右股静脉和右颈静脉分别置入两根导管。第5周采用Evans蓝染色稀释法测定各组大鼠血浆体积（PV）。测定红细胞压积、血浆白蛋白、总蛋白和肿瘤压，计算BV和血浆白蛋白含量。采用Nothem印迹法测定肝脏白蛋白mRNA水平，评价白蛋白合成。[结果]Ex组BV和血浆体积高于Con组（分别为6.4±0.2和4.8±0.5 ml/100g体重）（P<0.05）。血浆白蛋白含量（0.13±0.01 ml/100g体重）显著高于对照组（0.10±0.01 ml/100g体重）（P<0.05）。两组大鼠肝脏白蛋白mRNA表达相似。[结论]四周的跑步机运动可使BV升高。血浆白蛋白的增加可能是这种反应的一种机制。虽然白蛋白mRNA在肝脏中的表达在对照组和对照组之间保持不变，但运动训练可能在早期促进了白蛋白的合成。少

[Background] It is well known that exercise training is a potent stimulus to increase blood volume (BV), which is determined by many factors, i.e. renal water and Na^+ handling and fluid movement between the cellular and extracellular spaces. However, it remains unknown which factor is involved in the mechanism for the increase in BV due to exercise training.[Purpose] 1. Treadmill exercise can increase BV in rats -rats could be model animal to investigate the mechanism for BV increase-?2. Albumin, major substance maintaining plasma oncotic pressure, could be a factor increasing BV?[Methods] Rats were divided into two groups : exercise training and no training groups (Ex and Con, respectively, n=10 each). The Con group was housed in normal cages at 23℃ in LD 12:12 h. The Ex group was also housed in the same condition but had 1-h treadmill exercise for 4 weeks (5 days/week). The treadmill speed was set at 10 m/sec and the slope was increased from 0°to 15°every week. At the end of 3rd wee … More k, two catheter were placed in the right femoral and jugular veins, respectively. In 5th week plasma volume (PV) of each rat was determined by Evans Blue dye dilution technique. Hematocrit, plasma albumin and total protein and oncotic pressure were also measured, and BV and plasma albumin content were calculated. Albumin synthesis was evaluated by measuring albumin mRNA level in the liver using Nothem blotting technique.[Results] BV and plasma volume in the Ex group was greater (P<0.05) than in the Con group (6.4 ± 0.2 and 4.8 ± 0.5 ml/100g body weight, respectively). Plasma albumin content was also greater (P<0.05) than in the Con group (0.13 ± 0.01 and 0.10 ± 0.01 ml/100g body weight, respectively). The expression of albumin mRNA in the liver was similar in the two groups.[Conclusion] Four-week treadmill exercise could increase BV in rats. The increase in plasma albumin could be a mechanism for this response. Although the expression of albumin mRNA in the liver remained unchanged between the Ex and Con groups, exercise training may have facilitated albumin synthesis in the earlier period. Less