Shohet S B, Nathan D G, Karnovsky M L
J Clin Invest. 1968 May;47(5):1096-108. doi: 10.1172/JCI105799.
Mature human erythrocytes were incubated with (14)C-labeled palmitic acid bound to crystalline human albumin. Energy-dependent incorporation of the labeled palmitic acid into cell membrane phospholipids occurred, and various stages in this incorporation were defined. Initially the palmitic acid was rapidy transferred from the albumin to a "superficial" membrane pool of free fatty acid (F-1), which was removable when the cells were washed with defatted albumin. This process was independent of red cell metabolism. The labeled fatty acid then passed into a second "deeper" membrane pool of free fatty acids (F-2), which was not extractable with albumin. This process was energy-dependent and proceeded at a slower rate than the initial transfer from albumin to F-1. Ultimately the labeled fatty acid was incorporated into phosphatides (PL). This process also was dependent upon cellular metabolism. The kinetics of pulse label studies suggest that the processes observed were sequential and that precursor-product relationships exist between the F-1 and F-2 pools and the F-2 and PL pools. [Formula: see text] From the size and specific activities of these pools, calculations of the extent of phospholipid turnover were made. An approximate figure of 2% /hr or 30 nmoles/ml of packed red blood cells per hr was obtained. The figure was further calculated to represent an energy cost to the red blood cell of approximately 5% of the energy available from glycolysis.
将成熟的人类红细胞与结合在结晶人白蛋白上的（14）C标记的棕榈酸一起孵育。发生了标记棕榈酸的能量依赖性掺入细胞膜磷脂的过程，并确定了该掺入过程的各个阶段。最初，棕榈酸迅速从白蛋白转移到游离脂肪酸的“表面”膜池（F-1），当用脱脂白蛋白洗涤细胞时，该池中的棕榈酸是可去除的。这个过程与红细胞代谢无关。然后，标记的脂肪酸进入游离脂肪酸的第二个“更深层”膜池（F-2），该池不能用白蛋白提取。这个过程是能量依赖性的，并且比从白蛋白到F-1的初始转移速率要慢。最终，标记的脂肪酸被掺入磷脂（PL）中。这个过程也依赖于细胞代谢。脉冲标记研究的动力学表明，观察到的过程是连续的，并且F-1和F-2池以及F-2和PL池之间存在前体-产物关系。[公式：见正文]根据这些池的大小和比活性，计算了磷脂周转的程度。得到的近似数字是每小时2%或每小时每毫升压积红细胞30纳摩尔。进一步计算得出，这个数字代表红细胞的能量消耗约占糖酵解可利用能量的5%。
