Bhavnani B R, Wallace D G
Department of Obstetrics and Gynecology, St. Michael's Hospital, Ont., Canada.
Biochem Cell Biol. 1990 Oct;68(10):1210-7. doi: 10.1139/o90-179.
The metabolic pathways by which the glycogen is utilized by fetal tissues is not well established. In the present study the ontogeny of seven key enzymes involved in glycolysis and the tricarboxylic acid cycle has been established for rabbit fetal lung, heart, and liver. In the fetal lung the activities of phosphofructokinase, pyruvate kinase, lactic dehydrogenase, citrate synthase, and malate dehydrogenase increase from day 21 to 25. Thereafter the levels either drop to day 19 levels or do not change. The isocitrate dehydrogenase activity continues to increase from day 19 of gestation to maximum level on day 31 of gestation. In fetal heart the pattern of activity is similar, but in fetal liver most of the enzymes reach maximum levels earlier and, with the exception of pyruvate kinase, do not show a significant fall in activity near term. The pattern of development of pyruvate dehydrogenase complex is different; maximum activity is observed on day 27 in fetal lung and heart and on day 21 in fetal liver. These results indicate that all three fetal tissues can oxidize glucose. Also, the accumulation of glycogen, particularly in fetal lung, appears to ensure that at specific times during gestation adequate quantities of energy (ATP) and substrates, required for surfactant phospholipid synthesis, are available independent of maternal supply of glucose or during brief episodes of hypoxia.
胎儿组织利用糖原的代谢途径尚未完全明确。在本研究中，已确定了家兔胎儿肺、心脏和肝脏中参与糖酵解和三羧酸循环的七种关键酶的个体发生情况。在胎儿肺中，磷酸果糖激酶、丙酮酸激酶、乳酸脱氢酶、柠檬酸合酶和苹果酸脱氢酶的活性从第21天到第25天增加。此后，这些水平要么降至第19天的水平，要么没有变化。异柠檬酸脱氢酶的活性从妊娠第19天持续增加，在妊娠第31天达到最高水平。在胎儿心脏中，活性模式相似，但在胎儿肝脏中，大多数酶更早达到最高水平，并且除丙酮酸激酶外，在足月时活性没有显著下降。丙酮酸脱氢酶复合体的发育模式不同；在胎儿肺和心脏中，第27天观察到最大活性，在胎儿肝脏中，第21天观察到最大活性。这些结果表明，所有三种胎儿组织都可以氧化葡萄糖。此外，糖原的积累，特别是在胎儿肺中，似乎确保在妊娠期间的特定时间，有足够数量的能量（ATP）和表面活性剂磷脂合成所需的底物，而不依赖于母体葡萄糖供应或在短暂缺氧期间。
