Vargas F F, Sanabria P, Osorio H, Schulz C
Am J Physiol. 1986 Sep;251(3 Pt 2):H676-80. doi: 10.1152/ajpheart.1986.251.3.H676.
Hydraulic conductivity (Lp) of cava vein endothelium was obtained with a new method that measures fluid flow at constant volume. Dogs were anesthetized with pentobarbital sodium. A vessel segment was removed, cannulated, and hung free from a force transducer calibrated to measure weight. Hydraulic pressure difference drove fluid across the vessel wall. This fluid was washed out from the vessel surface by external perfusion, causing a weight loss that was transmitted to a Grass polygraph through the force transducer. Shifting the polygraph balance caused a voltage output which was used to activate a controller operating a microsyringe pump. By injecting fluid into the vessel lumen, this servomechanism counteracted weight changes and kept volume and pressure at a fixed level. Recording the volume injected allowed continuous monitoring of fluid flow. This avoided the problems caused by frequent pressure and volume resetting in previous methods. Fluid flow was a linear function of the applied pressure (r = 0.87). Lp was 0.91 +/- 0.05 (SD) X 10-7 cm X s-1 X cmH2O-1. This value was very similar to those in continuous capillaries and arterial endothelium.
采用一种在恒定体积下测量流体流量的新方法来获取腔静脉内皮的水力传导率（Lp）。用戊巴比妥钠对犬进行麻醉。取出一段血管，插管后悬挂在经校准可测量重量的力传感器上。液压差驱使流体穿过血管壁。通过外部灌注将该流体从血管表面冲洗掉，导致重量减轻，此重量减轻通过力传感器传递到Grass多导生理记录仪。移动多导生理记录仪的平衡装置会产生一个电压输出，该电压输出用于激活操作微量注射泵的控制器。通过向血管腔内注入流体，这种伺服机制抵消重量变化，并使体积和压力保持在固定水平。记录注入的体积可实现对流体流量的连续监测。这避免了先前方法中因频繁重置压力和体积而导致的问题。流体流量是所施加压力的线性函数（r = 0.87）。Lp为0.91±0.05（标准差）×10⁻⁷ cm×s⁻¹×cmH₂O⁻¹。该值与连续毛细血管和动脉内皮中的值非常相似。
