INFLUENCE OF HYPOXIA EXPOSURE ON THE ENERGY-METABOLISM OF COMMON CARP(CYPRINUS-CARPIO L.)

Hypoxic conditions is a common adverse environmental condition in an a quatic environment. To study the responses of fish to this phenomenon common carp (Cyprinus carpio L.) were exposed to a graded hypoxia load and the oxygen consumption was measured continuously. At 30%AS (air s aturation) 20%AS, 10%AS, 5%AS and 3%AS blood, liver and white muscle s amples were collected. In the blood, haematological parameters, substr ates (FFA, lactate and glucose), as well as the stress hormone cortiso l were measured. High-energy phosphorylated compounds and lactate were measured in liver and white muscle tissue. During hypoxia, ATP concen trations and the adenylate energy charge (AEC) remained constant in wh ite muscle, whereas both declined in liver tissue. The critical oxygen tension, which reflects the onset of a physiological or biochemical r esponse at a certain hypoxia load, indicates that rapid changes were r ecorded in the blood, followed by the liver while white muscle (except for phosphocreatine (PCr)) is rather insensitive to environmental hyp oxia. It is concluded that the impaired oxidative phosphorylation is c ompensated by the creatine kinase equilibrium reaction (depletion PCr pool) and the anaerobic glycolysis (lactate production).