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

[研究背景]运动训练是一种有效的增加血容量（blood volume，BV）的刺激手段，而血容量的增加是由多种因素决定的，如肾脏对水和Na^+的处理以及细胞与细胞外间隙之间的液体流动。然而，它仍然是未知的因素参与的机制，BV增加，由于运动训练。【目的】1.跑台运动可增加大鼠BV，大鼠可作为研究BV增加机制的模型动物。2.白蛋白是维持血浆onset压的主要物质，可能是增加BV的一个因素。[方法]将大鼠分为运动训练组和非运动训练组（分别为Ex组和Con组，n=10）。对照组在23℃下饲养于正常笼中，LD 12：12 h。Ex组也被安置在相同的条件下，但有1小时的跑步机运动4周（5天/周）。跑步机速度设定为10 m/s，每周将坡度从0°增加到15°。在第三周结束时 ...更多信息 k，分别在右侧股静脉和颈静脉放置两个导管。第5周用伊文思蓝染料稀释法测定血浆容量（PV）。同时测定红细胞压积、血浆白蛋白、总蛋白和血压，计算BV和血浆白蛋白含量。通过使用Nothem印迹技术测量肝脏中的白蛋白mRNA水平来评价白蛋白合成。[结果] Ex组BV和血浆容量（分别为6.4 ± 0.2和4.8 ± 0.5ml/100 g体重）高于Con组（P<0.05）。血浆白蛋白含量也高于对照组（分别为0.13 ± 0.01和0.10 ± 0.01 ml/100 g体重）（P<0.05）。肝组织中白蛋白mRNA的表达在两组中相似。[结论] 4周跑台运动可增加大鼠BV。血浆白蛋白的增加可能是这种反应的机制。虽然白蛋白mRNA在肝脏中的表达在Ex和Con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