ENERGY STATUS AND FREE FATTY-ACID PATTERNS IN TISSUES OF COMMON CARP (CYPRINUS-CARPIO, L) AND RAINBOW-TROUT (ONCORHYNCHUS-MYKISS, L) DURING SEVERE OXYGEN RESTRICTION

Common carp and rainbow trout were exposed to a severe level of oxygen restriction up to a near lethal value, to study the occurrence of tissue damage. Rainbow trout lost equilibrium at a PO2 of 3.2 kPa, whereas carp were able to survive 1.5 hr of anoxia. In both species, the anaerobic metabolism was significantly activated and the energy status (PCr, ATP and energy charge) was significantly depressed in brain, liver, and red and white muscle. No marked release of PUFA to the FFA pool was observed, while membrane leakage was not increased as evidenced by plasma LDH-activity. These results indicate the absence of a marked hydrolysis of membrane lipids. Thus, even after a near lethal exposure to hypoxia or anoxia, no tissue damage occurs in fish liver and skeletal muscles. The changes of the FFA patterns in the skeletal muscles and liver of both species after oxygen deprivation may be related to changes in desaturase activities, a reduction of lipolytic activity and PUFA metabolism.