Control of energy metabolism in fish white muscle.

Concentrations of key metabolites were determined in carp white muscle before exercise and after maximal activity. It was found that the concentration of ATP decreases by about 65%, ADP decreases slightly, and AMP remains unchanged. Consequently, the level of the free adenylate pool decreases. Simultaneously there is an increase in the concentration of IMP and NH4+. The increase in IMP level and the decrease in adenylate pool are essentially in 1:1 stoichiometry, a result showing that the adenylate pool is decreased by the reaction catalyzed by 5'-AMP deaminase (EC 3.5.4.6.). During exercise there is an increase in levels of glucose-6-phosphate, fructose 6-phosphate, and fructose 1,6-diphosphate that, along with the decrease in ATP levels, can account for the increase in glycolytic flux by activation of phosphofructokinase and pyruvate kinase.