Wolf M B, Porter L P, Scott D R, Zhang J X
Department of Physiology, School of Medicine, University of South Carolina, Columbia 29208.
J Appl Physiol (1985). 1992 Jul;73(1):166-72. doi: 10.1152/jappl.1992.73.1.166.
We investigated the effects of cold temperatures on microvascular protein permeability in the isolated constant-flow perfused cat hindlimb. The perfusates were 20% cat plasma-80% albumin-electrolyte solution (low-viscosity perfusate, approximately 1 cP) or whole blood (high-viscosity perfusate, approximately 4 cP). The time at low temperature (less than 10 degrees C) was less than 3 h (short term) or greater than 5 h (long term). Decreases in the solvent drag reflection coefficient (sigma f) indicated increases in permeability. The sigma f's were determined with the integral-mass balance method from measurement of changes in protein concentration and hematocrit induced by fluid filtration into the tissues. Short-term cold exposure did not increase permeability with either a low- or a high-viscosity perfusate, whereas long-term exposure with limb temperatures of approximately 5 degrees C significantly increased permeability when the perfusate was whole blood. In addition, we verified our previous prediction that flow had to be reduced to 6-8 ml.min-1.100 g-1 to avoid the hydrostatic edema caused by short-term perfusion with whole blood at approximately 5 degrees C. Also, we found that at approximately 3 degrees C histamine's permeability-increasing effect was totally abolished, whereas at approximately 20 degrees C this effect was partially inhibited. Hence, constant-flow perfusion at low temperature with whole blood can cause edema by a pressure-dependent mechanism, whereas long-term perfusion with this perfusate at low temperatures can cause a permeability increase that further compounds edema formation. Histamine is not responsible for this permeability increase.
我们研究了低温对离体恒流灌注猫后肢微血管蛋白通透性的影响。灌注液为20%猫血浆 - 80%白蛋白 - 电解质溶液（低粘度灌注液，约1厘泊）或全血（高粘度灌注液，约4厘泊）。低温（低于10摄氏度）持续时间小于3小时（短期）或大于5小时（长期）。溶剂拖曳反射系数（σf）降低表明通透性增加。σf通过积分质量平衡法测定，该方法通过测量因液体滤入组织而引起的蛋白质浓度和血细胞比容变化来确定。短期冷暴露在使用低粘度或高粘度灌注液时均未增加通透性，而当灌注液为全血时，在约5摄氏度的肢体温度下长期暴露会显著增加通透性。此外，我们验证了我们之前的预测，即流量必须降至6 - 8毫升·分钟-1·100克-1，以避免在约5摄氏度下用全血进行短期灌注所引起的静水压性水肿。而且，我们发现，在约3摄氏度时组胺的通透性增加作用完全消失，而在约20摄氏度时该作用受到部分抑制。因此，在低温下用全血进行恒流灌注可通过压力依赖性机制导致水肿，而在低温下用这种灌注液进行长期灌注可导致通透性增加，从而进一步加重水肿形成。组胺并非这种通透性增加的原因。
