Petersen K F, Vilstrup H, Tygstrup N
Division of Hepatology, Rigshospitalet, Copenhagen, Denmark.
Horm Metab Res. 1990 Dec;22(12):612-5. doi: 10.1055/s-2007-1004985.
The in vivo capacity of urea nitrogen synthesis (CUNS) during alanine stimulation was measured within the blood amino acid concentration interval 7.3-11.6 mmol/l, where urea synthesis is at maximum and independent of substrate concentration. Three groups of rats were fed for 14 days, either a low protein diet (8%), a normal diet (17%), or a high protein diet (53%). Diet protein modified both CUNS and plasma glucagon concentration. CUNS was 5.86 +/- 2.93, 7.43 +/- 2.16, and 19.31 +/- 4.32 mumol/(min.100 g BW) (mean +/- SD, N = 6), respectively. The corresponding plasma glucagon concentrations after alanine stimulation were 222 +/- 400, 633 +/- 229, and 1700 +/- 627 ng/l, respectively. The in vivo kinetics of urea production is regulated by dietary protein, possibly via glucagon. This implies that the liver plays an active part in adaptation of whole body nitrogen homeostasis to dietary changes.
在血液氨基酸浓度区间7.3 - 11.6 mmol/l内测量了丙氨酸刺激期间尿素氮合成（CUNS）的体内能力，在此区间尿素合成处于最大值且与底物浓度无关。三组大鼠分别喂食低蛋白饮食（8%）、正常饮食（17%）或高蛋白饮食（53%）14天。饮食蛋白质改变了CUNS和血浆胰高血糖素浓度。CUNS分别为5.86±2.93、7.43±2.16和19.31±4.32 μmol/（min·100 g体重）（平均值±标准差，N = 6）。丙氨酸刺激后相应的血浆胰高血糖素浓度分别为222±400、633±229和1700±627 ng/l。尿素生成的体内动力学可能通过胰高血糖素受饮食蛋白质调节。这意味着肝脏在使全身氮稳态适应饮食变化中发挥积极作用。
