Production of alanine and glutamine by atrial muscle from fed and fasted rats
Tischler, M.E.; Goldberg, A.L.
American Journal of Physiology 238(5): E487-E493
1980
ISSN/ISBN: 0002-9513 PMID: 7377343 Document Number: 164525
During incubation, rat atrial and rabbit papillary muscles synthesized and released large amounts of alanine and even greater amounts of glutamine. The amino groups used in the synthesis of alanine and glutamine seemed to be derived from the catabolism of other amino acids, specifically, leucine, isoleucine, valine, aspartate, glutamate, asparagine, arginine and proline. The total amount of glutamine and alanine synthesized increased by 45% in atrial muscle from starved rats, in which the oxidation of branched-chain amino acids is increased. In atria from fed rats, addition of leucine stimulated by about 20% the production of alanine and glutamine, probably by providing additional amino groups for transamination with alpha -ketoglutarate. In cardiac muscle from rats and rabbits deprived of food for 48 h, leucine increased the production of glutamine, but not of alanine. Isoleucine and valine, by contrast, increased production of alanine and glutamine in those tissues. In the presence of leucine, small amounts of pyruvate seem to limit the production of alanine, apparently because leucine, unlike isoleucine or valine, promotes the conversion of pyruvate to lactate.