Alterations of energy metabolism and (anti)oxidant status in red blood cells of carps (Cyprinus carpio L.) exposed to acute hypoxia

Abstract

Specimens of the carps (Cyprinus carpio L.) were adapted to the oxygen concentration of 6.5mg/L water (100%) as control (C) group. The first (H1) and second (H2) experimental groupswere exposed to progressive reduction of O2 to 4.2 mg/L (55%) during 115 hours and 2.3 mg/L(30%) during 230 hours, respectively. Acute hypoxia decreased glucose (H1) and pyruvate (H1and H2) concentrations in the blood of carps, while lactate level was significantly increased(H2). Concentration of red blood cells (RBCs) ATP was decreased in both (H1 and H2)groups of fish. Concomitant increase of ADP concentration was observed in (H2) group offish. The decrease of ATP/ADP ratio in (H2) group was also found. In carps of (H1) group,the activities of superoxide dismutase (SOD) and catalase (CAT) in RBCs were increasedwhereas glutathione-S-transferase (GST) activity in the plasma was increased in both groupsof fish. Glutathione peroxidase (GSH-Px) activity and the concentration of reducedglutathione (GSH) were decreased in the same conditions. Increased concentration of lipidperoxides (LP) in the blood of (H1 and H2) groups of animals in relation to the controls wasalso found. In conclusion, acute hypoxia induced a significant alteration of antioxidantenzyme activities and lipid peroxide concentration in the blood of carps (Cyprinus carpio L.)under influence of progressive reduction of oxygen concentration. All specified changes aredependent from duration of hypoxic conditions. The presented results suggest that during the evolution carps developed a well defined metabolic regulation and antioxidant defense systemfor the protection from acute hypoxia.