Nagasawa T, Funabiki R
J Biochem. 1981 Apr;89(4):1155-61.
N tau-Methylhistidine(3-methylhistidine) in urine of the rat is mainly derived from the degradation of actin and myosin in skeletal muscle, intestine and skin. The fractional degradation rates of the myosin-actin pools of these tissues were calculated from the time course of increase in the specific radioactivities of N tau-methylhistidine after daily administration of [methyl-14C]methionine to young adult rats under conditions of restricted food intake. The contributions to urinary excretion of N tau-methylhistidine from the three tissues were calculated from the fractional degradation rates and N tau-methylhistidine contents of the three tissues; 75.6% for skeletal muscle, 2.2% for intestine and 22.2% for skin. The results show that the skeletal muscle is the major source of urinary N-tau-methylhistidine output, but the contribution of skin is not negligible in rats. The specific radioactivity of N tau-methylhistidine in urine was much higher than that of skeletal muscle. The fractional degradation rates of myosin and actin in skeletal muscle had similar values. Although the specific radioactivities of N tau-methylhistidine in myosin and actin were very different, the mean value was similar to that in mixed skeletal muscle.
大鼠尿液中的N-甲基组氨酸（3-甲基组氨酸）主要来源于骨骼肌、肠道和皮肤中肌动蛋白和肌球蛋白的降解。在食物摄入量受限的条件下，每天给成年幼鼠注射[甲基-14C]蛋氨酸后，根据N-甲基组氨酸比放射性增加的时间进程，计算这些组织中肌球蛋白-肌动蛋白池的分解率。根据分解率和这三种组织中N-甲基组氨酸的含量，计算这三种组织对尿液中N-甲基组氨酸排泄的贡献；骨骼肌为75.6%，肠道为2.2%，皮肤为22.2%。结果表明，骨骼肌是尿液中N-甲基组氨酸排出的主要来源，但在大鼠中皮肤的贡献也不可忽视。尿液中N-甲基组氨酸的比放射性远高于骨骼肌。骨骼肌中肌球蛋白和肌动蛋白的分解率值相似。虽然肌球蛋白和肌动蛋白中N-甲基组氨酸的比放射性差异很大，但平均值与混合骨骼肌中的相似。
