Ishigami A, Reed T D, Roth G S
Molecular Physiology and Genetics Section, NIA, NIH, Francis Scott Key Medical Center, Baltimore, MD 21224.
Biochem Biophys Res Commun. 1993 Oct 15;196(1):181-6. doi: 10.1006/bbrc.1993.2232.
Epidermal growth factor (EGF) stimulated DNA synthesis and EGF receptor levels were examined in primary cultured hepatocytes from 6, 12 and 24 month old rats. EGF stimulated DNA synthesis began after 12h and reached a peak at 48 h. Although no age difference was seen in the time course of DNA synthesis, the magnitude of synthesis at the peak time in 12 and 24 month old rat hepatocytes was reduced approximately 50 and 70%, as compared to that at 6 months. Hepatocyte EGF receptors exhibited no age difference in the equilibrium dissociation constant (Kd) or the density (Bmax). These results indicate that EGF stimulated DNA synthesis in rat hepatocytes declines with age, and that this reduction is not due to decreased receptor density or specific binding affinity.
研究了表皮生长因子（EGF）对6个月、12个月和24个月大的大鼠原代培养肝细胞中DNA合成的刺激作用以及EGF受体水平。EGF刺激DNA合成在12小时后开始，并在48小时达到峰值。尽管在DNA合成的时间进程中未观察到年龄差异，但与6个月大的大鼠相比，12个月和24个月大的大鼠肝细胞在峰值时间的合成量分别减少了约50%和70%。肝细胞EGF受体在平衡解离常数（Kd）或密度（Bmax）方面没有年龄差异。这些结果表明，EGF刺激大鼠肝细胞DNA合成的能力随年龄下降，且这种下降不是由于受体密度或特异性结合亲和力降低所致。
