Mowbray J, Davies J A, Bates D J, Jones C J
Biochem J. 1975 Dec;152(3):583-92. doi: 10.1042/bj1520583.
Perfused rat heart incorporated L-[14C]tyrosine into protein at a constant rate for up to 75 min. A purified bovine growth-hormone preparation (1 mug/ml) stimulated the incorporation to a new constant rate that was more than three times the control rate by 10 min after hormone addition to perfusate. The hormone, however, did not alter the intracellular tracer amino acid pool, and the relationship of this to the aminoacyl-tRNA precursor pool is discussed. It is concluded that the increased incorporation largely reflected a rapid increase in protein synthesis at the ribosomes. Measurements of cyclic nucleotide contents during the perfusion showed that these appeared to vary in a systematic way during the perfusion. This strands in contrast with the constant values given by several other parameters measured in this preparation. Futher, the cyclic nucleotide variation seems to be independent of external effectors. The steady-state performance of the heart correlates more closely the [cyclic AMP]/[cyclic GMP] ratio than with the content of the individual cyclic nucleotides. At 10 min after the addition of growth hormone a slight decrese in cyclic AMP content and a large decrease in cyclic GMP were found, suggesting that the hormone's effect in stimulating protein synthesis may be mediated by a decrease in cyclic nucleotide concentrations or an increase in the [cyclic AMP]/[cyclic |p] ratio. The findings are also consistent with an intracellularly directed role for these nucleotides, and the possibility that the cyclic nucleotide changes are an indirect result of growth-hormone action is discussed.
灌注的大鼠心脏在长达75分钟的时间内以恒定速率将L-[14C]酪氨酸掺入蛋白质中。一种纯化的牛生长激素制剂（1微克/毫升）在将激素加入灌注液10分钟后刺激掺入达到一个新的恒定速率，该速率是对照速率的三倍多。然而，该激素并未改变细胞内示踪氨基酸池，并讨论了其与氨酰-tRNA前体池的关系。得出的结论是，掺入增加主要反映了核糖体处蛋白质合成的快速增加。灌注过程中对环核苷酸含量的测量表明，这些含量在灌注过程中似乎以系统的方式变化。这与该制剂中测量的其他几个参数的恒定值形成对比。此外，环核苷酸的变化似乎与外部效应物无关。心脏的稳态表现与[环磷酸腺苷]/[环磷酸鸟苷]比值的相关性比与单个环核苷酸的含量更密切。在添加生长激素10分钟后，发现环磷酸腺苷含量略有下降，环磷酸鸟苷大幅下降，这表明激素刺激蛋白质合成的作用可能是由环核苷酸浓度的降低或[环磷酸腺苷]/[环磷酸鸟苷]比值的增加介导的。这些发现也与这些核苷酸在细胞内的定向作用一致，并讨论了环核苷酸变化是生长激素作用的间接结果的可能性。
