Zhang J X, Wolf M B
Department of Physiology, University of South Carolina School of Medicine, Columbia 29208.
J Appl Physiol (1985). 1991 Aug;71(2):703-8. doi: 10.1152/jappl.1991.71.2.703.
We investigated the effects of low temperatures down to approximately 5 degrees C on postcapillary resistance (Rv) and isogravimetric capillary pressure (Pci) in the isolated constant-flow-perfused cat hindlimb to see if a low-temperature-induced increase in Rv and decrease in Pci could lead to an increase in filtration pressure and edema formation. A low-viscosity perfusate (20% cat plasma, 80% albumin-electrolyte solution; viscosity approximately 1 cP) was used. Isoproterenol (10(-7) M) was added to vasodilate the limb and achieve normal microvascular permeability. Rv and Pci were estimated from the slope and zero-flow intercept, respectively, of the straight-line fit to the isogravimetric venous pressure vs. flow data. Rv and Pci were determined in each experiment at an initial 37 degrees C control, at a lowered temperature (30, 23, 15, or 5-10 degrees C), and then at 37 degrees C again. The ratio of Rv at the low temperatures relative to the initial 37 degrees C control increased almost linearly as temperature was reduced. The increase was 3.4 times control at the lowest temperature. Pci decreased significantly from control only in the lowest temperature group where the change was -5.4 mmHg. Analysis of our data with the low-viscosity perfusate shows that the limb can become edematous if temperature is lowered to approximately 5 degrees C unless venous pressure (Pv) is lowered to venous collapse and flow reduced to less than approximately 20 ml.min-1.100g-1.(ABSTRACT TRUNCATED AT 250 WORDS)
我们研究了低至约5摄氏度的低温对离体恒流灌注猫后肢毛细血管后阻力（Rv）和等重力毛细血管压力（Pci）的影响，以观察低温诱导的Rv增加和Pci降低是否会导致滤过压升高和水肿形成。使用了低粘度灌注液（20%猫血浆，80%白蛋白电解质溶液；粘度约为1厘泊）。加入异丙肾上腺素（10^(-7) M）使肢体血管舒张并实现正常的微血管通透性。Rv和Pci分别根据等重力静脉压与流量数据的直线拟合斜率和零流量截距来估算。在每个实验中，分别在初始37摄氏度对照、降低温度（30、23、15或5 - 10摄氏度）时以及之后再次回到37摄氏度时测定Rv和Pci。低温下Rv相对于初始37摄氏度对照的比值几乎随温度降低呈线性增加。在最低温度时，该增加是对照的3.4倍。仅在最低温度组中Pci较对照显著降低，变化为 - 5.4 mmHg。对我们使用低粘度灌注液的数据进行分析表明，如果温度降至约5摄氏度，除非静脉压（Pv）降至静脉塌陷且流量降至小于约20 ml·min^(-1)·100g^(-1)，否则肢体可能会出现水肿。（摘要截短于250字）
