It has been shown recently that glutamine is taken up by the mouse kidney in vivo. However, knowledge about the fate of this amino acid and the regulation of its metabolism in the mouse kidney remains poor. Given the physiological and pathophysiological importance of renal glutamine metabolism and the increasing use of genetically modified mice in biological research, we have conducted a study to characterize glutamine metabolism in the mouse kidney. Proximal tubules isolated from fed and 48h-starved mice and then incubated with a physiological concentration of glutamine, removed this amino acid and produced ammonium ions at similar rates. In agreement with this observation, activities of the ammoniagenic enzymes, glutaminase and glutamate dehydrogenase, were not different in the renal cortex of fed and starved mice, but the glutamate dehydrogenase mRNA level was elevated 4.5-fold in the renal cortex from starved mice. In contrast, glucose production from glutamine was greatly stimulated whereas the glutamine carbon removed, that was presumably completely oxidized in tubules from fed mice, was virtually suppressed in tubules from starved animals. In accordance with the starvation-induced stimulation of glutamine gluconeogenesis, the activities and mRNA levels of glucose-6-phosphatase, and especially of phosphoenolpyruvate carboxykinase, but not of fructose-1,6-bisphosphatase, were increased in the renal cortex of starved mice. On the basis of our in vitro results, the elevated urinary excretion of ammonium ions observed in starved mice probably reflected an increased transport of these ions into the urine at the expense of those released into the renal veins rather than a stimulation of renal ammoniagenesis.
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November 2002
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Research Article|
November 15 2002
Effect of starvation on glutamine ammoniagenesis and gluconeogenesis in isolated mouse kidney tubules
Agnès CONJARD;
Agnès CONJARD
1
Laboratoire de Physiopathologie Métabolique et Rénale, Institut National de la Santé et de la Recherche Médicale, U499, Faculté de Médecine R.T.H. Laennec, rue G. Paradin, 69372 Lyon Cedex 08, France
1To whom correspondence should be addressed (e-mail [email protected]).
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Virginie BRUN;
Virginie BRUN
Laboratoire de Physiopathologie Métabolique et Rénale, Institut National de la Santé et de la Recherche Médicale, U499, Faculté de Médecine R.T.H. Laennec, rue G. Paradin, 69372 Lyon Cedex 08, France
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Mireille MARTIN;
Mireille MARTIN
Laboratoire de Physiopathologie Métabolique et Rénale, Institut National de la Santé et de la Recherche Médicale, U499, Faculté de Médecine R.T.H. Laennec, rue G. Paradin, 69372 Lyon Cedex 08, France
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Gabriel BAVEREL;
Gabriel BAVEREL
Laboratoire de Physiopathologie Métabolique et Rénale, Institut National de la Santé et de la Recherche Médicale, U499, Faculté de Médecine R.T.H. Laennec, rue G. Paradin, 69372 Lyon Cedex 08, France
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Bernard FERRIER
Bernard FERRIER
Laboratoire de Physiopathologie Métabolique et Rénale, Institut National de la Santé et de la Recherche Médicale, U499, Faculté de Médecine R.T.H. Laennec, rue G. Paradin, 69372 Lyon Cedex 08, France
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Publisher: Portland Press Ltd
Received:
February 26 2002
Revision Received:
July 17 2002
Accepted:
August 06 2002
Accepted Manuscript online:
August 06 2002
Online ISSN: 1470-8728
Print ISSN: 0264-6021
The Biochemical Society, London ©2002
2002
Biochem J (2002) 368 (1): 301–308.
Article history
Received:
February 26 2002
Revision Received:
July 17 2002
Accepted:
August 06 2002
Accepted Manuscript online:
August 06 2002
Citation
Agnès CONJARD, Virginie BRUN, Mireille MARTIN, Gabriel BAVEREL, Bernard FERRIER; Effect of starvation on glutamine ammoniagenesis and gluconeogenesis in isolated mouse kidney tubules. Biochem J 15 November 2002; 368 (1): 301–308. doi: https://doi.org/10.1042/bj20020331
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