Goldspink D F, Kelly F J
Biochem J. 1984 Jan 15;217(2):507-16. doi: 10.1042/bj2170507.
Changes in the growth and protein turnover (measured in vivo) of the rat liver, kidney and whole body were studied between 16 days of life in utero and 105 weeks post partum. Tissue and whole-body growth were related to changes in both cellular hyperplasia (i.e. changes in DNA) and hypertrophy (protein/DNA values) and to the protein composition within the enlarging tissue mass. The suitability of using a single large dose of phenylalanine for measuring the rates of protein synthesis during both pre- and post-natal life was established. The declining growth rates in the whole animal and the two visceral tissues were then explained by developmental changes in the fractional rates of protein synthesis and breakdown, turnover rates being age-for-age higher in the liver than in the kidney, which in turn were higher than those measured in the whole animal. The declining fractional rates of synthesis in both tissues and the whole body with increasing age were related to changes in the tissues' ribosomal capacity and activity. The fall in the hepatic rate between 18 and 20 days of foetal life (from 134 to 98% per day) corresponded to a decrease in both the ribosomal capacity and the rate of synthesis per ribosome. No significant changes in any of these parameters were, however, found in the liver between weaning (3 weeks) and senility (105 weeks). In contrast, the fractional synthetic (and degradative) rates progressively declined in the kidney (from 95 to 24% per day) and whole body (from 70 to 11% per day) throughout both pre- and post-natal life, mainly as a consequence of a progressive decline in the ribosomal capacity, but with some fall in the ribosomal activity also during foetal life. The age-related contributions of these visceral tissues to the total amount of protein synthesized per day by the whole animal were determined. The renal contribution remained fairly constant at 1.6-2.9%, whereas the hepatic contribution declined from 56 to 11%, with increasing age. Approximate-steady-state conditions were reached at, and between, 44 and 105 weeks post partum, the half-life values of mixed whole-body, kidney and liver proteins being 6.4, 3.0 and 1.5 days, respectively, at 105 weeks.
研究了大鼠肝脏、肾脏和全身在子宫内16天至产后105周期间的生长和蛋白质周转（体内测量）变化。组织和全身生长与细胞增生（即DNA变化）和肥大（蛋白质/DNA值）的变化以及增大的组织块内的蛋白质组成有关。确定了使用单一大剂量苯丙氨酸测量产前和产后蛋白质合成速率的适用性。然后通过蛋白质合成和分解的分数速率的发育变化来解释整个动物和两个内脏组织生长速率的下降，肝脏的周转率在同年龄时高于肾脏，而肾脏又高于整个动物的测量值。随着年龄的增长，两个组织和全身合成分数速率的下降与组织核糖体容量和活性的变化有关。胎儿期18至20天肝脏速率的下降（从每天134%降至98%）对应于核糖体容量和每个核糖体合成速率的下降。然而，在断奶（3周）至衰老（105周）期间，肝脏中这些参数均未发现显著变化。相比之下，在产前和产后整个生命过程中，肾脏（从每天95%降至24%）和全身（从每天70%降至11%）的合成（和降解）分数速率逐渐下降，主要是由于核糖体容量的逐渐下降，但在胎儿期核糖体活性也有一些下降。确定了这些内脏组织对整个动物每天合成的蛋白质总量的年龄相关贡献。肾脏的贡献保持在1.6 - 2.9%相当恒定，而肝脏的贡献随着年龄的增长从56%降至11%。产后44至105周及之间达到近似稳态条件，在105周时，全身、肾脏和肝脏混合蛋白质的半衰期值分别为6.4天、3.0天和1.5天。
