Hansen B A, Krog B, Vilstrup H
Scand J Clin Lab Invest. 1986 Oct;46(6):599-603. doi: 10.3109/00365518609083719.
The relationship between insulin concentration (32-980 mU/l) and the capacity of urea-N synthesis (CUNS) was investigated with alanine as nitrogen source in 26 nephrectomized rats. The blood glucose concentration was kept constant by the 'glucose clamp' technique, and the endocrine pancreatic response was controlled by somatostatin. The CUNS was determined as the accumulation of urea corrected for intestinal hydrolysis at a constant amino acid concentration within the interval 7.3-11.6 mmol/l. At insulin concentration above 200 mU/l CUNS was decreased from 10 to 6 mumol (min X 100 g body wt)-1. At lower insulin concentrations the decrease was proportional. Hyperglycaemia 14.8 mmol/l decreased CUNS to 6.3 mumol (min X 100 g body wt)-1. The basal rate of urea-N synthesis was reduced from 3.8 to 1.9 mumol (min X 100 g body wt)-1 by insulin concentrations above 200 mU/l. The estimated alanine elimination (5.8 mumol(min X 100 g body wt)-1) was unchanged by insulin and reduced to 3.3 mumol(min X 100 g body wt)-1) by hyperglycaemia. Somatostatin infusion had no effect on CUNS or alanine elimination. It is suggested that the capacity of urea-N synthesis is subject to short term regulation independently by insulin and glucose.
以丙氨酸为氮源，在26只肾切除大鼠中研究了胰岛素浓度（32 - 980 mU/l）与尿素氮合成能力（CUNS）之间的关系。通过“葡萄糖钳夹”技术使血糖浓度保持恒定，并用生长抑素控制胰腺内分泌反应。CUNS的测定方法是，在氨基酸浓度恒定于7.3 - 11.6 mmol/l区间内，对经肠道水解校正后的尿素积累量进行测定。当胰岛素浓度高于200 mU/l时，CUNS从10降至6 μmol（分钟×100克体重）-1。在较低胰岛素浓度下，下降呈比例关系。血糖浓度为14.8 mmol/l时，CUNS降至6.3 μmol（分钟×100克体重）-1。胰岛素浓度高于200 mU/l时，尿素氮合成的基础速率从3.8降至1.9 μmol（分钟×100克体重）-1。估计的丙氨酸清除率（5.8 μmol（分钟×100克体重）-1）不受胰岛素影响，但高血糖使其降至3.3 μmol（分钟×100克体重）-1。输注生长抑素对CUNS或丙氨酸清除率无影响。研究表明，尿素氮合成能力受胰岛素和葡萄糖的独立短期调节。
