Aminoacyl-tRNA and tissue free amino acid pools are equilibrated after a flooding dose of phenylalanine
Aminoacyl-tRNA and tissue free amino acid pools are equilibrated after a flooding dose of phenylalanine
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DOI：
10.1152/ajpendo.1999.277.1.e103
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发表时间：
1999-07-01
影响因子：
5.1
通讯作者：
Burrin, DG
中科院分区：
文献类型：
--
作者：
Davis, TA;Fiorotto, ML;Burrin, DG
用于测量组织蛋白质合成的泛液剂量法假设氨酰-tRNA库与组织和血液游离氨基酸库之间的同位素标记平衡。然而，这尚未在体内研究中验证苯丙氨酸示踪剂。我们确定了[H-3]苯丙氨酸的氨酰-tRNA和骨骼肌和肝脏的组织和血液游离氨基酸池的[H-3]苯丙氨酸的比放射性洪水剂量的苯丙氨酸沿着[H-3]苯丙氨酸一起给药后30分钟。在禁食和再喂食状态下以及在高胰岛素-血糖-氨基酸钳夹期间对新生猪进行研究。结果表明，30分钟后的洪水剂量的苯丙氨酸管理，有平衡的比放射性的苯丙氨酸之间的血液，组织，和tRNA前体池。骨骼肌和肝脏中蛋白质合成的三种前体池的比放射性平衡。无论是喂养，也不影响胰岛素状态的氨酰-tRNA的比放射性相对于组织游离氨基酸的比放射性。结果支持的假设，即组织游离氨基酸池比放射性是一个有效的措施的前体池比放射性，因此可以用来计算蛋白质合成率在骨骼肌和肝脏时，洪水剂量的苯丙氨酸管理。
The flooding dose method, which is used to measure tissue protein synthesis, assumes equilibration of the isotopic labeling between the aminoacyl-tRNA pool and the tissue and blood free amino acid pools. However, this has not been verified for a phenylalanine tracer in an in vivo study. We determined the specific radioactivity of [H-3]phenylalanine in the aminoacyl-tRNA and the tissue and blood free amino acid pools of skeletal muscle and liver 30 min after administration of a flooding dose of phenylalanine along with [H-3]phenylalanine. Studies were performed in neonatal pigs in the fasted and refed states and during hyperinsulinemiceuglycemic-amino acid clamps. The results showed that, 30 min after the administration of a flooding dose of phenylalanine, there was equilibration of the specific radioactivity of phenylalanine among the blood, tissue, and tRNA precursor pools. Equilibration of the specific radioactivity of the three precursor pools for protein synthesis occurred in both skeletal muscle and liver. Neither feeding nor insulin status affected the aminoacyl-tRNA specific radioactivity relative to the tissue free amino acid specific radioactivity. The results support the assumption that the tissue free amino acid pool specific radioactivity is a valid measure of the precursor pool specific radioactivity and thus can be used to calculate protein synthesis rates in skeletal muscle and liver when a flooding dose of phenylalanine is administered.