Halperin M L, Kamel K S
St. Michael's Hospital Annex, Lab No. 1, Toronto, Ont., Canada.
Miner Electrolyte Metab. 1990;16(5):277-82.
The metabolism of a typical North American diet yields a net acid load. Hydrogen ions are removed from the body after combining with bicarbonate to form CO2. This leaves the body with a deficit of bicarbonate. The role of the kidney is to add 'new' bicarbonate to the body. It does so primarily by synthesizing NH4+ plus bicarbonate while making NH4+ an end-product of metabolism (excreting it in the urine). Production of NH4+ occurs primarily in proximal convoluted tubule cells. Although several possible pathways can do this, the primary one stimulated by chronic metabolic acidosis is the glutaminase/glutamate dehydrogenase one. The upper limit on this pathway is set by energy turnover considerations. This, in effect, means control by renal work (sodium reabsorption) and fuel competitions (availability of fat-derived fuels).
典型的北美饮食代谢会产生净酸负荷。氢离子与碳酸氢根结合形成二氧化碳后从体内排出。这使得体内碳酸氢根缺乏。肾脏的作用是向体内添加“新的”碳酸氢根。它主要通过合成NH4+和碳酸氢根，同时使NH4+成为代谢终产物（通过尿液排出）来实现这一点。NH4+的产生主要发生在近端小管细胞中。虽然有几种可能的途径可以做到这一点，但慢性代谢性酸中毒刺激的主要途径是谷氨酰胺酶/谷氨酸脱氢酶途径。该途径的上限由能量周转因素决定。实际上，这意味着受肾脏工作（钠重吸收）和燃料竞争（脂肪衍生燃料的可用性）的控制。
