STUDIES ON IGF-I SIGNAL CASCADE ON MUSCLE PROTEIN RETENTION

研究了蛋氨酸和（或）甘氨酸缺乏对培养基199培养的鸡胚成肌细胞蛋白质合成的影响。所有成分均溶于Dulbecco改性磷酸盐缓冲盐水的Medium 199中培养的蛋白质合成显著低于所有成分均溶于水的Medium 199。虽然Medium 199缺乏蛋氨酸会降低成肌细胞蛋白的合成，但缺乏甘氨酸不会影响成肌细胞蛋白的合成。蛋氨酸和甘氨酸缺乏对成肌细胞蛋白合成没有相互作用。研究了培养基199中添加亮氨酸和胎牛血清（FCS）对鸡胚成肌细胞蛋白质合成和降解的影响。培养基199中含有0、1、2、5、10% FCS和457（培养基199中亮氨酸的原始浓度）、2287、4574μmol亮氨酸/l。亮氨酸和FCS浓度对体外肌肉蛋白合成有交互作用。当培养基中不含FCS时，培养基中亮氨酸浓度从2287 μmol/l增加到4574 μmol/l，促进了成肌细胞蛋白的合成。当培养基199中加入1 ~ 2%的FCS时，培养基中亮氨酸浓度从457 μmol/l增加到2287 μmol/l，促进成肌细胞蛋白质合成，亮氨酸浓度更高时，不促进成肌细胞蛋白质合成。在培养液中FCS含量大于5%时，高亮氨酸浓度（4574μmol/l）下的成肌细胞蛋白合成显著低于低亮氨酸水平下的成肌细胞蛋白合成。未观察到亮氨酸和FCS浓度对肌肉蛋白降解的相互作用。培养液中FCS浓度从0增加到5%，降低了鸡胚成肌细胞的蛋白质降解，在更高水平上对蛋白质降解无显著影响。当培养基中亮氨酸浓度从457 μmol/l增加到2287μmol/l时，鸡胚成肌细胞对蛋白质的降解降低。而高浓度的亮氨酸（4457μmol/l）对鸡胚成肌细胞的蛋白质降解没有影响。少

Influence of methionine and/or glycine deficiency on protein synthesis of chicken embryo myoblasts cultured in Medium 199 was examined. Protein synthesis cultured in Medium 199 in which all ingredients were solved in Dulbecco's modified phosphate buffered saline was dramatically lower than that in Medium 199 in which all ingredients were solved in water. Although methionine deficiency from Medium 199 decreased myoblast protein synthesis, glycine deficiency did not affect. There was no interaction between methionine and glycine deficiency on myoblast protein synthesis.The influence of leucine and fetal calf serum (FCS) in Medium 199 on protein synthesis and degradation of chicken embryo myoblasts was examined. Medium 199 included 0, 1, 2, 5, 10% FCS and 457 (original concentration of leucine in Medium 199), 2287, 4574μmol leucine/l. There was an interaction between leucine and FCS concentrations on muscle protein synthesis in vitro. When FCS was not included in Medium 199, myoblast prot … More ein synthesis was stimulated with an increment in leucine concentration in the medium from 2287 to 4574 μmol/l. When 1 or 2% of FCS was included in Medium 199, myoblast protein synthesis was stimulated by increasing leucine concentration in the medium from 457 to 2287 μmol/l, and at the higher level of leucine, protein synthesis was not stimulated. At more than 5% of FCS in the medium, myoblast protein synthesis at higher concentration of luecine of 4574μmol/l was significantly lower than those of lower leucine levels.No interaction between leucine and FCS concentrations on muscle protein degradation Was observed. Protein degradation of chicken embryo myoblasts was decreased by an increment of FCS concentration in the medium from 0 to 5%, and at the higher level no significant influence was observed. When leucine concentration of in the medium was increased from 457 to 2287μmol/l, protein degradation of chicken embryo myoblasts was decreased. But high concentration of leucine at 4457μmol/l did not affect protein degradation of chicken embryo myoblasts. Less