Toback F G, Smith P D, Lowenstein L M
J Clin Invest. 1974 Jul;54(1):91-7. doi: 10.1172/JCI107754.
Membrane metabolism was studied during the initiation of compensatory growth after acute reduction in renal mass. The rate of [(14)C]choline incorporation into phospholipid in renal cortical slices was increased by 37% at 5 min of compensatory growth in mice. The rate increased to the maximal value of 68% by 20 min and remained there for 3 h. The rate then remained increased at 28-34% above normal for 2 days and returned to normal by the 6th day. The increase in rate of choline incorporation into renal phospholipid was independent of choline uptake. [(14)C]Choline was found to be a specific precursor of the three renal phospholipids, phosphatidylcholine, lysophosphatidylcholine, and sphingomyelin, which comprise over half the amount of the phospholipids. The relative distribution of the label in each of the three phospholipid classes did not change with compensatory growth. An increased rate of choline incorporation was also observed in kidneys of rats during compensatory growth and in the compensating kidneys of mice treated with indomethacin before uninephrectomy. The rate was increased 24% at 3 h after uninephrectomy in vivo. The increase appeared to be specific for the kidney, since it did not occur in the livers of these mice. The results indicate that the onset of renal compensatory growth is associated with a specific enhancement of the synthesis of renal choline-containing phospholipids. Since the phospholipids largely occur in the cell membrane, early alterations in cell membrane metabolism may thus play a role in the initiation of cell growth.
在肾质量急性减少后的代偿性生长启动过程中，对膜代谢进行了研究。在小鼠代偿性生长5分钟时，肾皮质切片中[(14)C]胆碱掺入磷脂的速率增加了37%。到20分钟时，该速率增加到最大值68%，并在3小时内保持不变。然后在2天内该速率保持在比正常水平高28 - 34%，到第6天恢复正常。胆碱掺入肾磷脂的速率增加与胆碱摄取无关。[(14)C]胆碱被发现是三种肾磷脂（磷脂酰胆碱、溶血磷脂酰胆碱和鞘磷脂）的特异性前体，这三种磷脂占磷脂总量的一半以上。在代偿性生长过程中，三种磷脂类中每种的标记相对分布没有变化。在大鼠代偿性生长期间以及在单侧肾切除术前用吲哚美辛处理的小鼠的代偿性肾脏中，也观察到胆碱掺入速率增加。在体内单侧肾切除术后3小时，该速率增加了24%。这种增加似乎是肾脏特有的，因为在这些小鼠的肝脏中没有发生。结果表明，肾代偿性生长的启动与含肾胆碱磷脂合成的特异性增强有关。由于磷脂主要存在于细胞膜中，因此细胞膜代谢的早期改变可能在细胞生长启动中起作用。
