Häussinger D
Medizinische Universitätsklinik, Freiburg.
Klin Wochenschr. 1990 Nov 16;68(22):1096-101. doi: 10.1007/BF01798059.
Hepatic and renal nitrogen metabolism are linked by an interorgan glutamine flux, coupling both renal ammoniagenesis and hepatic ureogenesis to systemic acid base regulation. This is because protein breakdown produces equimolar amounts of NH4+ and HCO3-. A hepatic role in this interorgan team effort is based upon the tissue-specific presence of urea synthesis, which represents a major irreversible pathway for removal of metabolically generated bicarbonate. A sensitive and complex control of bicarbonate disposal via ureogenesis by the extracellular acid-base status creates a feed-back control loop between the acid-base status and the rate of bicarbonate elimination. This bicarbonate-homeostatic mechanism operates without threat of hyperammonemia, because a sophisticated structural and functional organisation of ammonia-metabolizing pathways in the liver acinus uncouples urea synthesis from the vital need to eliminate potentially toxic ammonia.
肝脏和肾脏的氮代谢通过器官间谷氨酰胺通量相联系，将肾脏氨生成和肝脏尿素生成与全身酸碱调节耦合起来。这是因为蛋白质分解产生等摩尔量的NH4+和HCO3-。肝脏在这一器官间协作中的作用基于尿素合成在组织中的特异性存在，尿素合成是代谢产生的碳酸氢盐清除的主要不可逆途径。细胞外酸碱状态通过尿素生成对碳酸氢盐处置进行敏感而复杂的控制，在酸碱状态和碳酸氢盐消除速率之间形成了一个反馈控制环。这种碳酸氢盐稳态机制在没有高氨血症威胁的情况下运行，因为肝腺泡中氨代谢途径复杂的结构和功能组织将尿素合成与消除潜在有毒氨的迫切需求分离开来。
