Peculiarities of organization of tissue metabolism in molluscs with different tolerance to external hypoxia

Oxygen consumption, content of several carbohydrate metabolites, and activities of their coupled enzymes were studied in bivalve molluscs with different tolerance to oxygen deficit: Mytilus galloprovincialis Lam. (black morpha) and Anadara Inaequivalvis Br. It has been shown that under conditions of external normoxia the anadara resistance to hypoxia preserves anaerobic orientation of metabolism. Its tissues are distinguished by high activities of malate and lactate dehydrogenases with the decreased content of glucose and the increased level of lactate. In several organs the succinate thiokinase and fumarate reductase reactions are realized, which is indicated by elevated activities of the alanine and aspartate aminotransferases. The anaerobic orientation of protein metabolism is added by a high pool of free amino acids and the elevated urea content in the mollusc tissues. The total orientation of metabolism in the anadara tissues rules out a significant lactate accumulation and determines low requirement of its organism in oxygen.