Glutamine synthesis from aspartate in guinea-pig renal cortex.
1. Glutamine was found to be the main carbon and nitrogen product of the metabolism of aspartate in isolated guinea-pig kidney-cortex tubules. Glutamate, ammonia and alanine were only minor products. 2. Carbon-balance calculations and the release of 14CO2 from [U-14C]aspartate indicate that oxidation of the aspartate carbon skeleton occurred. 3. A pathway involving aspartate aminotransferase, glutamate dehydrogenase, glutamine synthetase, phosphoenolpyruvate carboxykinase, pyruvate kinase, pyruvate dehydrogenase and enzymes of the tricarboxylic acid cycle is proposed for the conversion of aspartate into glutamine. 4. Evidence for this pathway was obtained by: (i) inhibiting aspartate removal by amino-oxyacetate, an inhibitor of transaminases, (ii) the use of methionine sulphoximine, an inhibitor of glutamine synthetase, which induced a large increase in ammonia release from aspartate, (iii) the use of quinolinate, an inhibitor of phosphoenolpyruvate carboxykinase, which inhibited glutamine synthesis from aspartate, (iv) the use of alpha-cyano-4-hydroxycinnamate, an inhibitor of the mitochondrial transport of pyruvate, which caused an accumulation of pyruvate from aspartate, and (v) the use of fluoroacetate, an inhibitor of aconitase, which inhibited glutamine synthesis with concomitant accumulation of citrate from aspartate.
Baverel
G
G
Laboratoire de Physiologie Rénale et Métabolique, INSERM U80, Faculté de Médecine Alexis Carrel, Lyon, France.
Martin
G
G
Michoudet
C
C
D000625:Aminooxyacetic Acid / Q000378:metabolism; D000643:Ammonium Chloride / Q000378:metabolism; D000818:Animals; D001219:Aspartate Aminotransferases / Q000378:metabolism*; D001224:Aspartic Acid / Q000378:metabolism* / Q000494:pharmacology; D002250:Carbon Radioisotopes; D003373:Coumaric Acids / Q000494:pharmacology; D005463:Fluoroacetates / Q000494:pharmacology; D005969:Glutamate Dehydrogenase / Q000378:metabolism*; D005973:Glutamine / Q000096:biosynthesis; D006168:Guinea Pigs; D007684:Kidney Tubules / Q000187:drug effects / Q000378:metabolism*; D008717:Methionine Sulfoximine / Q000378:metabolism; D009584:Nitrogen / Q000378:metabolism; D010071:Oxaloacetates / Q000378:metabolism; D011805:Quinolinic Acids / Q000494:pharmacology
D002250:Carbon Radioisotopes; D003373:Coumaric Acids; D005463:Fluoroacetates; D010071:Oxaloacetates; D011805:Quinolinic Acids; D000643:Ammonium Chloride; D005973:Glutamine; D000625:Aminooxyacetic Acid; D008717:Methionine Sulfoximine; C007175:alpha-cyano-4-hydroxycinnamate; D001224:Aspartic Acid; C014815:fluoroacetic acid; D005969:Glutamate Dehydrogenase; D001219:Aspartate Aminotransferases; D009584:Nitrogen