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Utilization of alanine for glucose formation in isolated rabbit kidney‐cortex tubules
Author(s) -
Zabłocki Krzysztof,
Bryła Jadwiga
Publication year - 1989
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(89)81514-5
Subject(s) - gluconeogenesis , alanine , biochemistry , amino acid , chemistry , extracellular , medicine , renal cortex , substrate (aquarium) , l glucose , endocrinology , biology , kidney , metabolism , insulin , ecology , islet
In kidney cortex tubules isolated from fed rabbits L‐alanine is not utilized as glucose precursor, when added as a sole substrate. However, this amino acid decreases gluconeogenesis from low (up to 1 mM) 2‐oxoglutarate concentrations and stimulates this process at higher (2.5–10 mM) ketoacid contents in the suspension medium. Aminooxyacetate, an inhibitor of aminotransferases, abolishes both inhibitory and stimulatory effects of L‐alanine on glucose formation. The addition of 2‐oxoglutarate increases the incorporation of L‐[U‐ 14 C]alanine to glucose from 8‐ to 123‐fold, depending upon the ketoacid and alanine concentrations used. In contrast, nonlabelled L‐alanine decreases the incorporation of low [U‐ 14 C)2‐oxoglutarate concentrations into glucose, while it does not affect contribution of 5 mM ketoacid to gluconeogenesis. The data indicate that (i) in the presence of 2‐oxoglutarate L‐alanine is utilized as glucose precursor in rabbit renal tubules and (ii) this amino acid may decrease the contribution of low extracellular concentrations of the ketoacid to gluconeogenesis.