Influence of Hypoxia Exposure On the Energy Metabolism of Common Carp (Cyprinus Carpio L.)

Abstract

Hypoxic conditions is a common adverse environmental condition in an aquatic 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 saturation) 20%AS, 10%AS, 5%AS and 3%AS blood, liver and white muscle samples were collected. In the blood, haematological parameters, substrates (FFA, lactate and glucose), as well as the stress hormone cortisol were measured. High-energy phosphorylated compounds and lactate were measured in liver and white muscle tissue. During hypoxia, ATP concentrations and the adenylate energy charge (AEC) remained constant in white muscle, whereas both declined in liver tissue. The critical oxygen tension, which reflects the onset of a physiological or biochemical response at a certain hypoxia load, indicates that rapid changes were recorded in the blood, followed by the liver while white muscle (except for phosphocreatine (PCr)) is rather insensitive to environmental hypoxia. It is concluded that the impaired oxidative phosphorylation is compensated by the creatine kinase equilibrium reaction (depletion PCr pool) and the anaerobic glycolysis (lactate production).