Freedman M L
New York University Medical Center, New York 10016.
Blood Cells. 1987;13(1-2):227-35.
Cells from aged animals show a decrease in heme synthesis, an increase in heme degradation, and a maintenance of heme concentration and heme-containing proteins. This raises the possibility that alternate sources of heme are utilized by the old animal to maintain intracellular heme necessary for initiation of protein synthesis. The mechanisms to balance heme and protein synthesis, and cytoplasmic and mitochondrial protein synthesis remain intact with advanced age. Iron remains available to the healthy organism in abundant amounts throughout the life span. The decrease in cellular iron utilization seen with age might conceivably result from availability of heme independent of heme synthesis, as intracellular heme controls the cellular uptake of iron from transferrin. Heme levels in aged cells seem to be maintained via an alternate heme source. The bone marrow in aged animals appears to function adequately as long as there is no stress. Anemia, therefore, should always be considered as a serious sign in illness and never as a normal concomitant of aging.
老年动物的细胞显示出血红素合成减少、血红素降解增加，以及血红素浓度和含血红素蛋白质的维持。这增加了一种可能性，即老年动物利用血红素的替代来源来维持蛋白质合成起始所需的细胞内血红素。随着年龄增长，平衡血红素与蛋白质合成以及细胞质和线粒体蛋白质合成的机制仍然完好无损。在整个生命周期中，健康生物体都有大量的铁可用。随着年龄增长而出现的细胞铁利用减少，可能是由于血红素的可用性独立于血红素合成，因为细胞内血红素控制着从转铁蛋白摄取铁的过程。老年细胞中的血红素水平似乎通过替代血红素来源得以维持。只要没有应激，老年动物的骨髓似乎就能充分发挥功能。因此，贫血应始终被视为疾病的严重迹象，而绝不是衰老的正常伴随现象。
