The regulation of glucose and pyruvate formation from glutamine and citric-acid-cycle intermediates in the kidney cortex of rats, dogs, rabbits and guinea pigs
| Autor: | Guy Lemieux, Patrick Vinay, Malcolm Watford, André Gougoux |
|---|---|
| Rok vydání: | 1980 |
| Předmět: |
medicine.medical_specialty
Kidney Cortex Glutamine Citric Acid Cycle Guinea Pigs In Vitro Techniques Biology Biochemistry Dogs Internal medicine medicine Animals Citrate synthase Picolinic Acids Pyruvates Molecular Biology Gluconeogenesis Cell Biology Rats Pyruvate carboxylase Citric acid cycle Kidney Tubules Oxaloacetate decarboxylase Endocrinology Lactates biology.protein Ketoglutaric Acids Rabbits Phosphoenolpyruvate carboxykinase Pyruvate kinase Research Article |
| Zdroj: | Biochemical Journal. 188:741-748 |
| ISSN: | 0264-6021 |
| DOI: | 10.1042/bj1880741 |
| Popis: | The suppression by 3-mercaptopicolinate of gluconeogenesis from glutamine or 2-oxoglutarate in rat or dog kidney tubules did not affect the amount of these substrates undergoing complete oxidation. Furthermore, 3-mercaptopicolinate caused an accumulation of lactate in dog tubules. 3-Mercaptopicolinate abolished both gluconeogenesis and substrate oxidation in tubules from rabbit and guinea-pig kidney. These results imply the presence of an alternative pathway to phosphoenolpyruvate carboxykinase/pyruvate kinase for the production of pyruvate from citric-acid-cycle intermediates in the kidney cortex of rats and dogs but not in that of rabbits or guinea pigs. Oxaloacetate decarboxylase (present in the kidney cortex of all four species) or ‘malic’ enzyme (present in rat and dog but absent in rabbit and guinea-pig kidney cortex) could function in this role. Our observations indicate that ‘malic’ enzyme is probably implicated in this phenomenon. The lactate production observed in dog tubules in the presence of 3-mercaptopicolinate can be suppressed when aspartate formation is inhibited by 2-amino-4-methoxy-trans-but-3-enoic acid. This suggests that the provision of cytosolic NADH from citric-acid-cycle intermediates is facilitated by accumulation of aspartate acting as a ‘sink’ for cytosolic oxaloacetate. |
| Databáze: | OpenAIRE |
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