Wiklund L
Department of Anesthesiology, Uppsala University Hospital, Sweden.
Ups J Med Sci. 1996;101(1):35-67. doi: 10.3109/03009739609178913.
Systemic metabolism results in a production of not only carbon dioxide, water and urea but also bicarbonate ions. Most of these bicarbonate ions are generated during the catabolism of glutamine. In order to be eliminated as carbon dioxide in the lungs bicarbonate ions must be protonised. This protonisation of the bicarbonate ion seems to take place in a number of tissue compartments in which acid-base balance is maintained. One of the most important processes for protonisation of the bicarbonate ion is the hepatic ureagenesis from ammonia/ammonium ions. A substantial part of the ammonia/ammonium ions are generated during the catabolism of amino acids. Terminal oxidation of glutamine in the gut seems to be of great significance for this process. In certain conditions the enteric generation of ammonium ions seems so important that an ATP-driven enterohepatic recirculation of ammonium ions/urea constituting an amplifying mechanism for the protonisation of the bicarbonate ion is motivated.
全身代谢不仅会产生二氧化碳、水和尿素，还会产生碳酸氢根离子。这些碳酸氢根离子大部分是在谷氨酰胺分解代谢过程中产生的。为了在肺部以二氧化碳的形式排出，碳酸氢根离子必须被质子化。碳酸氢根离子的这种质子化似乎发生在许多维持酸碱平衡的组织隔室中。碳酸氢根离子质子化的最重要过程之一是肝脏从氨/铵离子生成尿素。氨/铵离子的很大一部分是在氨基酸分解代谢过程中产生的。肠道中谷氨酰胺的终末氧化似乎对这个过程具有重要意义。在某些情况下，肠道产生铵离子似乎非常重要，以至于促使形成一种由ATP驱动的铵离子/尿素肠肝循环，这构成了碳酸氢根离子质子化的一种放大机制。
