Heir S, Wiig H
Department of Physiology, University of Bergen, Norway.
Acta Physiol Scand. 1988 Jul;133(3):365-71. doi: 10.1111/j.1748-1716.1988.tb08418.x.
We collected interstitial fluid for measurement of colloid osmotic pressure (COPi) of normally hydrated and dehydrated rats with two methods: (1) saline-soaked nylon-wicks implanted in vivo for 1 h; and (2) the crossover method, i.e. titration with wicks pre-loaded with serial dilutions of rat plasma implanted post mortem for 15-20 min. All wicks were implanted in subcutis on the back. Dehydration was induced by injection of 40 mg furosemide followed by 24 h water deprivation. The saline-soaked wick method gave an average control COPi of 10.8 mmHg, 2-3 mmHg lower than the corresponding pressure obtained with the crossover method. This discrepancy between the methods increased to 10-11 mmHg in dehydrated animals, indicating that the saline-soaked wick method underestimates COPi even more during dehydration than during control conditions. The mean COPi of 22.8 mmHg (SD = 3.7, n = 9) obtained in dehydrated rats using the crossover method corresponds well with what is to be expected from the reduction in interstitial fluid volume. The present study suggests that the frequently used implantation period for saline-soaked wicks of 60 min should be prolonged to 90-120 min. It further shows that the rise in COPi is about 3 times more important than the fall in interstitial fluid hydrostatic pressure in restricting mobilization of interstitial fluid during dehydration.
我们采用两种方法收集正常水合及脱水大鼠的间质液，以测量胶体渗透压（COPi）：（1）将生理盐水浸泡的尼龙芯植入体内1小时；（2）交叉法，即使用死后植入15 - 20分钟的预先装载了系列稀释大鼠血浆的芯进行滴定。所有芯均植入背部皮下。通过注射40mg呋塞米，随后24小时禁水来诱导脱水。生理盐水浸泡芯法测得的平均对照COPi为10.8mmHg，比交叉法获得的相应压力低2 - 3mmHg。在脱水动物中，两种方法之间的差异增加到10 - 11mmHg，这表明生理盐水浸泡芯法在脱水期间比在对照条件下更低估COPi。使用交叉法在脱水大鼠中获得的平均COPi为22.8mmHg（标准差= 3.7，n = 9），与间质液体积减少所预期的结果相符。本研究表明，生理盐水浸泡芯常用的植入时间60分钟应延长至90 - 120分钟。它还表明，在脱水期间限制间质液动员方面，COPi的升高比间质液静水压的降低重要约3倍。
