INCREASE IN ANTERIOR TIBIALIS MUSCLE PROTEIN-SYNTHESIS IN HEALTHY MAN DURING MIXED AMINO-ACID INFUSION - STUDIES OF INCORPORATION OF [1-C-13]LEUCINE
INCREASE IN ANTERIOR TIBIALIS MUSCLE PROTEIN-SYNTHESIS IN HEALTHY MAN DURING MIXED AMINO-ACID INFUSION - STUDIES OF INCORPORATION OF [1-C-13]LEUCINE
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DOI：
10.1042/cs0760447
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发表时间：
1989-04-01
期刊：
影响因子：
6
通讯作者：
RENNIE, MJ
中科院分区：
文献类型：
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作者：
BENNET, WM;CONNACHER, AA;RENNIE, MJ
1. 七名健康吸收后男性的前胫骨肌肉蛋白质合成是通过在启动的连续输注 L-[1-13C]亮氨酸期间肌肉蛋白质结合亮氨酸富集的增加来确定的。开始输注亮氨酸后 30 分钟（此时血浆 13C 富集稳定）、240 分钟后继续禁食期间以及输注混合氨基酸溶液 240 分钟后再次进行活检，混合氨基酸溶液使血浆总氨基酸浓度增加 37%。血浆α-酮异己酸中13C的平均富集被用作亮氨酸代谢前体池富集的指数。 2. 禁食期间胫骨前肌混合蛋白合成率为 0.055 (SD 0.008) %/h，输注混合氨基酸期间平均增加 35%，达到 0.074 (SD 0.021) %/h (P < 0.05)。 3. 禁食期间全身蛋白质分解（表示为血浆中内源亮氨酸出现的比率）为121 (SD 8) .mu.mol h-1 kg-1，并且在氨基酸输注期间平均下降（P < 0.01）12%。禁食期间亮氨酸氧化为 18 (SD 3) .mu.mol h-1 kg-1 ，氨基酸输注期间增加 (P < 0.001) 89%。禁食期间全身蛋白质合成（非氧化亮氨酸消失）为 104 (SD 6) .mu.mol h-1 kg-1 ，混合氨基酸输注期间上升 13% (P < 0.001)。 4.肌肉游离亮氨酸的 13C 富集仅为血浆α-酮异己酸中的 61 (SD 19)%，并且在混合氨基酸输注期间增加至 74 (SD 16)% (P < 0.02)。 5. 结果表明，氨基酸可用性的增加可将全身蛋白质平衡从负平衡逆转为正平衡，其中一个主要组成部分是肌肉蛋白质合成的增加。
1. Anterior tibial muscle protein synthesis in seven healthy postabsorptive men was determined from increases in muscle protein bound leucine enrichment during a primed continuous infusion of L-[1-13C]leucine. Biopsies were taken 30 min after the beginning of leucine infusion (when plasma 13C enrichment was steady), 240 min later during continued fasting and again after 240 min of infusion of a mixed amino acid solution which increased plasma total amino concentrations by 37%. The mean enrichment of 13C in plasma .alpha.-ketoisocaproate was used as an index of the enrichment of the precursor pool for leucine metabolism. 2. Anterior tibial muscle mixed protein synthetic rate during fasting was 0.055 (SD 0.008) %/h and this increased by an average of 35% during infusion of mixed amino acid to 0.074 (SD 0.021) %/h (P < 0.05). 3. Whole-body protein breakdown (expressed as the rate of endogenous leucine appearance in plasma) was 121 (SD 8) .mu.mol h-1 kg-1 during fasting and decreased (P < 0.01) by an average of 12% during amino acid infusion. Leucine oxidation was 18 (SD 3) .mu.mol h-1 kg-1 during fasting and increased (P < 0.001) by 89% during amino acid infusion. Whole-body protein synthesis (nonoxidative leucine disappearance) was 104 (SD 6) .mu.mol h-1 kg-1 during fasting and rose by 13% (P < 0.001) during mixed amino acid infusion. 4. 13C enrichment of muscle free leucine was only 61 (SD 19)% of that in plasma .alpha.-ketoisocaproate and this increased to 74 (SD 16)% (P < 0.02) during mixed amino acid infusion. 5. The results suggest that increased availability of amino acids reverses whole-body protein balance from negative to positive and a major component of this is the increase in muscle protein synthesis.