Udall J N, Bloch K J, Newman A P, Dixon M, Walker W A
Am J Physiol. 1984 Aug;247(2 Pt 1):G183-8. doi: 10.1152/ajpgi.1984.247.2.G183.
Earlier studies have shown that the uptake of intact proteins from the intestinal lumen into the systemic circulation is increased in neonates. The present experiments tested the uptake of trypsin in newborn compared with 4-wk-old weaned rabbits. Trypsin (200 mg/100 g body wt) was administered by gavage to newborn and 4-wk-old rabbits. Four hours later, the tryptic activity and immunoreactive trypsin (i-trypsin) content of serum from newborn rabbits exceeded that of the older animals. After Sephadex G-200 gel filtration of serum from animals gavaged with trypsin, tryptic activity was detected in the excluded volume (presumably reflecting trypsin bound to alpha 2-macroglobulin), and i-trypsin was detected in the included volume (presumably reflecting trypsin bound to alpha 1-antitrypsin). In vitro experiments demonstrated that large amounts of trypsin were required to overwhelm the antiprotease present in normal rabbit serum. We suggest that complete or partial deficiencies of serum protease inhibitors may permit proteases taken up from the intestinal lumen of the neonate to circulate, reach the liver, and induce tissue injury at this site.
早期研究表明，新生儿肠道腔内完整蛋白质进入体循环的摄取量会增加。本实验测试了新生兔与4周龄断奶兔对胰蛋白酶的摄取情况。将胰蛋白酶（200mg/100g体重）经口灌胃给予新生兔和4周龄兔。4小时后，新生兔血清中的胰蛋白酶活性和免疫反应性胰蛋白酶（i-胰蛋白酶）含量超过了年长动物。对经胰蛋白酶灌胃的动物血清进行葡聚糖凝胶G-200凝胶过滤后，在排阻体积中检测到胰蛋白酶活性（可能反映与α2-巨球蛋白结合的胰蛋白酶），在包含体积中检测到i-胰蛋白酶（可能反映与α1-抗胰蛋白酶结合的胰蛋白酶）。体外实验表明，需要大量胰蛋白酶才能克服正常兔血清中存在的抗蛋白酶。我们认为，血清蛋白酶抑制剂的完全或部分缺乏可能会使从新生儿肠道腔内摄取的蛋白酶得以循环，到达肝脏，并在该部位诱导组织损伤。
