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观察了运动性低铁状态大鼠骨髓细胞转铁蛋白(Tf)结合铁和非Tf结合铁摄入的变化。大鼠随机分为6个月的运动组(EG)和对照组(SG)。SG平均每个幼红细胞Tf受体数为890 150±164 849个,而在EG为2175 360±462 737个(P<0.05),但受体的解离常数不受运动影响。EG中Tf的内吞平台和胞内铁聚积速度显著高于SG,胞浆和胞内膜成分中Tf结合铁和Fe(Ⅱ)摄入增加。EG的胞浆内Fe(Ⅱ)摄入的米氏常数值降低;细胞膜成分中Fe(Ⅱ)摄入的最大速度增加。上述结果表明:运动不仅通过增加Tf受体的表达促进Tf结合铁的内吞,而且增强非Tf结合铁的内吞途径。尽管这些变化的机制尚不清楚,但它们有利于运动时血红素的合成。
The changes of Tf-bound iron and non-Tf bound iron in bone marrow of exercise-induced low-iron-status rats were observed. Rats were randomly divided into 6-month exercise group (EG) and control group (SG). The average number of Tf receptors per erythrocyte in SG was 890 150 ± 164 849, while in EG it was 2175 360 ± 462 737 (P <0.05), but the dissociation constants of the receptors were not affected by exercise. The Tf-endocytic and intracellular iron accumulation rate in EG was significantly higher than that in SG, and Tf-binding Fe and Fe (Ⅱ) uptake in cytoplasm and intracellular membrane increased. The Michaelis-Menten constant of Fe (Ⅱ) uptake in cytoplasm of EG decreased and the maximum speed of Fe (Ⅱ) uptake in cell membrane increased. The above results indicate that exercise not only promotes Tf-bound iron endocytosis by increasing Tf receptor expression, but also enhances the non-Tf-bound iron endocytosis pathway. Although the mechanism of these changes is not clear, they favor hemoglobin synthesis during exercise.