Chikenji T, Elwyn D H, Kinney J M
J Surg Res. 1983 Jan;34(1):68-82. doi: 10.1016/0022-4804(83)90023-9.
Measurement of protein synthesis in individual organs is important in understanding metabolic changes in injury, sepsis, or starvation. Methods, mostly isotopic, for measuring synthesis are plagued by problems of experimental design and interpretation. Thus it is desirable to use a variety of methods based on different assumptions. The present study is the first to isolate radioactive aminoacyl-tRNA in the study of protein synthesis in muscle and skin. Male rats, 200-300 g, trained to eat chow for 4 hr/day were studied at 2 hr (absorptive) or 16 hr (postabsorptive) after a meal. Under ether anesthesia, a tracer dose of L-[4-5-3H(N)]-lysine was infused at a constant rate. At 20, 30, or 40 min 1 ml of arterial blood was withdrawn and 2-g samples of skin and thigh muscle were quickly excised and frozen. Samples were pooled from 4 to 7 rats for each infusion period. Concentrations and specific activities were determined for plasma lysine, and for free, tRNA, and protein-bound lysine in muscle and skin. Protein renewal rates in absorptive and postabsorptive periods averaged 6 and 9% per day in muscle, and 20 and 35% in skin. The data for muscle confirms results of other methods and suggests little contribution of rapidly turning over protein. The contribution of skin to whole body protein synthesis, about 500 mg . 100 g-1 . day-1, is similar in magnitude to the contributions of muscle, liver, or intestine.
测量各个器官中的蛋白质合成对于理解损伤、脓毒症或饥饿时的代谢变化非常重要。测量合成的方法大多是同位素法，存在实验设计和解释方面的问题。因此，使用基于不同假设的多种方法是可取的。本研究首次在肌肉和皮肤蛋白质合成研究中分离出放射性氨酰 - tRNA。选用体重200 - 300克、经训练每天进食4小时的雄性大鼠，在进食后2小时（吸收期）或16小时（吸收后期）进行研究。在乙醚麻醉下，以恒定速率注入示踪剂量的L - [4 - 5 - 3H(N)] - 赖氨酸。在20、30或40分钟时，抽取1毫升动脉血，并迅速切除2克皮肤和大腿肌肉样本并冷冻。每个输注时间段从4至7只大鼠中采集样本。测定血浆赖氨酸以及肌肉和皮肤中游离、tRNA结合和蛋白质结合赖氨酸的浓度和比活性。吸收期和吸收后期肌肉中的蛋白质更新率平均分别为每天6%和9%，皮肤中为20%和35%。肌肉的数据证实了其他方法的结果，并表明快速周转蛋白质的贡献很小。皮肤对全身蛋白质合成的贡献约为500毫克·100克-1·天-1，在数量上与肌肉、肝脏或肠道的贡献相似。
