The Renal Handling of Citrate
Second-year medical students already know that citric acid is an especially valuable substance. They learn that of the metabolic processes in the body, the “citric acid cycle” is of utmost importance: not only is this the final metabolic pathway of glucose but also it is the pathway for many other substrates. Thus, nobody will doubt that citrate is a valuable metabolic substrate. However, against all expectations the kidney seems to handle this substance rather carelessly. Examination of the total urinary output shows a daily loss of more than 3 mmol which is 5 times the amount contained in plasma or approximately the entire pool in the total extracellular fluid. But we also know that Mother Nature is not wasteful. All other substrates and fuels in our metabolism are preserved most carefully and only traces of glucose, amino acids, fatty acids, and the like appear in urine.
KeywordsFiltration Depression Citrate Luminal Peri
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