Daudi I, Saba T M, Lewis M, Lewis E, Blumenstock F A, Gudewicz P, Malik A B, Fenton J W
Department of Physiology, Albany Medical College, New York.
Lab Invest. 1989 Nov;61(5):539-47.
Fibronectin is an adhesive glycoprotein found in plasma and lymph as well as between lung endothelial cells and their collagenous basement membranes. Fibronectin is highly sensitive to proteolytic cleavage. We determined if fragments of fibronectin appear in lung lymph in association with increased lung protein clearance after thrombin-induced intravascular coagulation. Thrombin was infused intravenously, (80 units/kg for 30 minutes) into sheep (n = 8) surgically prepared with chronic lung lymph fistulas. Plasma and lymph fibronectin was assayed by electroimmunoassay. Fibronectin fragments were detected using Western blot analysis. After thrombin infusion, lymph flow increased 650% above baseline within 1-2 hours in association with a 35% decline in lymph-to-plasma total protein concentration ratio. This was followed by a second phase (3.5-6 hours) of normalized lymph-to-plasma ratios coupled with sustained elevation of lymph flow. Lung protein clearance remained elevated (p less than 0.10) for 5.5 hours. Plasma fibronectin levels declined slightly over 1-5 hours (zero time = 597 +/- 64 micrograms/ml; 1.5 hours = 478 +/- 59 micrograms/ml) and then increased significantly (p less than 0.05) over 24-48 hours (760 +/- 85 micrograms/ml). The amount of low molecular weight fibronectin fragments in lung lymph increased over the 1.5-6 hours post-thrombin and then declined over 12-48 hours. Thus after thrombin infusion, fragments of fibronectin were usually detected in increased amounts of lung lymph in association with an elevation of lung protein clearance.
纤连蛋白是一种存在于血浆、淋巴以及肺内皮细胞与其胶原性基底膜之间的黏附糖蛋白。纤连蛋白对蛋白水解切割高度敏感。我们研究了在凝血酶诱导的血管内凝血后，纤连蛋白片段是否会出现在肺淋巴中，并与肺蛋白清除增加相关。将凝血酶静脉注射（80单位/千克，持续30分钟）到经手术制备有慢性肺淋巴瘘的绵羊（n = 8）体内。通过电免疫测定法检测血浆和淋巴中的纤连蛋白。使用蛋白质免疫印迹分析检测纤连蛋白片段。注射凝血酶后，1 - 2小时内淋巴流量比基线增加650%，同时淋巴与血浆总蛋白浓度比下降35%。随后是第二阶段（3.5 - 6小时），淋巴与血浆比值恢复正常，同时淋巴流量持续升高。肺蛋白清除在5.5小时内保持升高（p < 0.10）。血浆纤连蛋白水平在1 - 5小时内略有下降（零时间 = 597 ± 64微克/毫升；1.5小时 = 478 ± 59微克/毫升），然后在24 - 48小时内显著升高（p < 0.05）（760 ± 85微克/毫升）。肺淋巴中低分子量纤连蛋白片段的量在凝血酶注射后的1.5 - 6小时内增加，然后在12 - 48小时内下降。因此，注射凝血酶后，通常在肺淋巴量增加的情况下检测到纤连蛋白片段，同时肺蛋白清除升高。
