Sanabria P, Vargas F F
Department of Physiology and Biophysics, Medical School, University of Puerto Rico, San Juan 00936.
Am J Physiol. 1988 Sep;255(3 Pt 2):H638-45. doi: 10.1152/ajpheart.1988.255.3.H638.
The effect of bovine and dog albumin and plasma was measured on the hydraulic conductivity (Lp) and electrical resistance (R) across the endothelium of the dog vena cava. An estimate of changes in size of transendothelial water channels was then obtained by combining Lp and R values. Dogs were anesthetized with pentobarbital sodium to surgically remove their thoracic inferior vena cava. Lp was measured by a gravimetric method at constant vessel volume. R was obtained from the transvascular voltage changes caused by current pulses. Lp measured at the beginning of the experiments was 0.97 +/- 0.17 X 10(-7) cm.s-1.cmH2O-1 in plasma and 2.75 +/- 0.48 X 10(-7) cm.s-1.cmH2O-1 in Ringer solution. Bovine albumin produced an 18% reduction in Lp relative to its value in Ringer solution. Dog albumin and plasma lowered Lp 50 and 54%, respectively. The differences were statistically significant with P less than 0.05. R increased from 15.17 +/- 7.0 to 26.5 +/- 16.0 omega.cm2 in dog albumin and 27.4 +/- 9.6 omega.cm2 in dog plasma. Calculations using a model for the transendothelial channel and equations for Lp and R showed a decrease in channel width of 172 A due to the protein. This could be accounted for by the thickness of a monolayer of albumin absorbed to the channel walls. Results suggest that the permeability response to plasma proteins is a general property of vascular endothelium.
测定了牛白蛋白、狗白蛋白及血浆对狗腔静脉内皮水力传导率（Lp）和电阻（R）的影响。然后通过合并Lp和R值来估算跨内皮水通道大小的变化。用戊巴比妥钠麻醉狗，以便手术切除其胸段下腔静脉。在恒定血管容积下用重量法测量Lp。R是由电流脉冲引起的跨血管电压变化获得的。实验开始时，血浆中测得的Lp为0.97±0.17×10⁻⁷cm·s⁻¹·cmH₂O⁻¹，林格液中为2.75±0.48×10⁻⁷cm·s⁻¹·cmH₂O⁻¹。与林格液中的值相比，牛白蛋白使Lp降低了18%。狗白蛋白和血浆分别使Lp降低了50%和54%。差异具有统计学意义，P＜0.05。在狗白蛋白中，R从15.17±7.0增加到26.5±16.0Ω·cm²，在狗血浆中增加到27.4±9.6Ω·cm²。使用跨内皮通道模型以及Lp和R的方程进行计算表明，蛋白质使通道宽度减少了172埃。这可以用吸附在通道壁上的单层白蛋白的厚度来解释。结果表明，对血浆蛋白的通透性反应是血管内皮的一个普遍特性。
