ISSN:
1438-2199
Keywords:
Amino acids
;
Alanine
;
Fatty acids
;
Glutamine and glutamate synthesis
;
Glycerol and lactate metabolism
;
Malate-aspartate shuttle
;
Rabbit kidney-cortex tubules
;
Renal gluconeogenesis
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Summary In isolated rabbit renal cortical tubules, glucose synthesis from 1 mM alanine is negligible, while the amino acid is metabolized to glutamine and glutamate. The addition of 0.5 mM octanoate plus 2 mM glycerol induces incorporation of [U-14C]Alnine into glucose and decreases glutamine synthesis, whereas oleate and palmitate in the presence of glycerol are less potent than octanoate. Gluconeogenesis is also significantly accelerated when glycerol is substituted by lactate. In view of an increase in14CO2 fixation and elevation of both cytosolic and mitochondrial NADH/NAD+ ratios, the activation of glucose formation from alanine upon the addition of glycerol and octanoate is likely due to (i) stimulation of pyruvate carboxylation, (ii) increased availability of NADH for glyceraldehyde-3-phosphate dehydrogenase and (iii) elevation of mitochondrial redox state causing a diminished provision of ammonium for glutamine synthesis. The induction of gluconeogenesis in the presence of alanine, glycerol and octanoate is not related to cell volume changes. The results presented in this paper show the importance of free fatty acids and glycerol for regulation of renal gluconeogenesis from alanine. The possible physiological significance of the data is discussed.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01318884
Permalink
