Effect of a protein-free diet on muscle protein turnover and nitrogen conservation in euthyroid and hyperthyroid rats.
Effect of a protein-free diet on muscle protein turnover and nitrogen conservation in euthyroid and hyperthyroid rats.
复制标题
无蛋白饮食对甲状腺功能正常和甲状腺功能亢进大鼠肌肉蛋白周转和氮保存的影响。
DOI：
10.1042/bj2170471
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发表时间：
1984
期刊：
影响因子：
--
通讯作者：
Faas,FH
中科院分区：
文献类型：
--
作者：
Carter,WJ;vanderWeijdenBenjamin,WS;Faas,FH
虽然骨骼肌中的蛋白质周转在甲状腺功能亢进时增加，在甲状腺功能减退时减少，但蛋白质摄入不足往往会增加血清 T3（三碘甲状腺原氨酸），同时降低肌肉蛋白质周转。为了确定这种饮食引起的蛋白质周转减少是否可以独立于甲状腺状态而发生，我们检查了以无蛋白质饮食喂养的甲状腺功能亢进大鼠的肌肉蛋白质周转和氮保存。通过给予20微克T3/100克体重诱发甲状腺功能亢进后。连续 7 天，每天将甲状腺功能正常和甲状腺功能亢进的动物分为亚组，分别喂基础饮食和无蛋白质饮食。通过N tau-甲基组氨酸排泄和[14C]酪氨酸输注来测量肌肉蛋白质周转率。还测量了以无蛋白饮食喂养的甲状腺功能正常和甲状腺功能亢进动物的尿氮排出量。尽管甲状腺功能亢进增加了肌肉蛋白质合成和降解的基线速率，但它并不能阻止这些值因蛋白质消耗而降低。此外，甲状腺功能亢进大鼠对无蛋白饮食的反应显示氮排泄大大减少，尽管与甲状腺功能正常大鼠的数值不同。这些发现表明，蛋白质消耗使实验动物对 T3 的蛋白质分解代谢作用的反应减弱。
Although protein turnover in skeletal muscle is increased in hyperthyroidism and decreased in hypothyroidism, a deficient protein intake tends to increase serum T3 (tri-iodothyronine) while decreasing muscle protein turnover. To determine whether this diet-induced decrease in protein turnover can occur independent of thyroid status, we have examined muscle protein turnover and nitrogen conservation in hyperthyroid rats fed on a protein-free diet. After inducing hyperthyroidism by giving 20 micrograms of T3/100g body wt. daily for 7 days, groups of euthyroid and hyperthyroid animals were divided into subgroups fed on basal and protein-free diets. Muscle protein turnover was measured by N tau-methylhistidine excretion and [14C]tyrosine infusion. Urinary nitrogen output of euthyroid and hyperthyroid animals fed on the protein-free diet was also measured. Although hyperthyroidism increased the baseline rates of muscle protein synthesis and degradation, it did not prevent a decrease in these values in response to protein depletion. Furthermore, hyperthyroid rats showed greatly decreased nitrogen excretion in response to the protein-free diet, although not to values for euthyroid rats. These findings suggest that protein depletion made the experimental animals less responsive to the protein-catabolic effects of T3.