Energy metabolism and adenylate system in Mytilus galloprovincialis (Lamarck, 1819) tissues under acute hypoxia

The present study investigated the impact of acute hypoxia on key enzymes and products of energy metabolism in Mytilus galloprovincialis (Lamarck, 1819) tissues under experimental conditions. The response to hypoxia was tissue-specific. We found that anaerobic processes increased in the gills and foot, where the concentrations of glucose and pyruvate increased. In the gills, this was accompanied by higher succinate dehydrogenase (SDH) and aldolase activities. Concurrently, in the foot we observed a significant decrease in lactate dehydrogenase (LDH) activity and no change in lactate concentration, indicating suppression of the glucose-lactate metabolic pathway. At the same time, both tissues exhibited a significant increase in octopine dehydrogenase (OcDH) activity, indicating a shift of metabolism to the glucose-opine (octopine) pathway under hypoxia. The hepatopancreas acted as a donor of carbohydrate substrates. Glucose and lactate contents there decreased significantly. Metabolic reorganisation was accompanied by a decrease in ATP content in all tissues, a decrease in the adenylate pool and a loss of adenylate energy charge (AEC), indicating low efficiency of the glucose-opine pathway which is typical of the genus Mytilus.