Narbonne J F, Daubeze M, Bonmort F
Ann Nutr Aliment. 1978;32(1):59-75.
Parameters of skeletal muscle protein synthesis was studied in vivo and in vitro. The experimental design was previously described. Muscle humidity, protein and DNA content are not modified by vitamin A deficiency. RNA and free amino acids are modified. Glutamine, serine and threonine level decrease while phenylalanine and leucine increase in vitamin A deficients. After a single intra-peritoneal injection of (14C) leucine, the incorporation of radioactivity into total ribosomes and postribosomal supernatant protein was studied. The rats were killed 20, 40, 60 minutes and 2,6,10 days after injections. The half time for radioactivity accumulation was four times higher into total and ribosomal protein, two times higher into postribosomal supernatant protein in vitamin A deficient rats than in well-fed rats. The decay of acid soluble radioactivity was similar in the two groups, although protein synthesis was lowered by vitamin A deficiency. It was then supposed that leucine, enters into other metabolic paths. Sedimentation analysis in sucrose gradients revealed a lower proportion of higher ribosomes species in muscle of deficient rat than in normal ones, but ribosomes from deficients were more active for protein synthesis in vitro than ribosomes from well-fed rats. The vitamin A deficiency decrease the muscle protein synthesis and lead to important changes on in vitro and in vivo ribosomal activity.
对骨骼肌蛋白质合成的参数进行了体内和体外研究。实验设计先前已作描述。维生素A缺乏不会改变肌肉湿度、蛋白质和DNA含量，但会改变RNA和游离氨基酸含量。维生素A缺乏的大鼠体内，谷氨酰胺、丝氨酸和苏氨酸水平降低，而苯丙氨酸和亮氨酸水平升高。单次腹腔注射（14C）亮氨酸后，研究了放射性物质掺入总核糖体和核糖体后上清液蛋白质的情况。在注射后20、40、60分钟以及2、6、10天处死大鼠。维生素A缺乏的大鼠体内，放射性物质在总核糖体蛋白和核糖体蛋白中的积累半衰期是正常喂养大鼠的四倍，在核糖体后上清液蛋白中的积累半衰期是正常喂养大鼠的两倍。尽管维生素A缺乏会降低蛋白质合成，但两组中酸溶性放射性物质的衰减情况相似。因此推测，亮氨酸进入了其他代谢途径。蔗糖梯度沉降分析显示，缺乏维生素A的大鼠肌肉中较高核糖体种类的比例低于正常大鼠，但缺乏维生素A的大鼠的核糖体在体外蛋白质合成方面比正常喂养大鼠的核糖体更活跃。维生素A缺乏会降低肌肉蛋白质合成，并导致体内外核糖体活性发生重要变化。
