GILL CARBOHYDRATE-METABOLISM OF RAINBOW-TROUT IS MODIFIED DURING GRADUAL ADAPTATION TO SEA-WATER

The levels of glycogen and glucose, and the activities of several key enzymes of glycogenolysis, glycolysis and the pentose phosphate shunt were assessed in gills of rainbow trout of two sizes (97.03 +/- 3.03 g and 165.69 +/- 5.01 g) during gradual transfer to sea water (0, 9, 18 and 28 ppt). The results indicated changes, mainly size-independent, in carbohydrate metabolism of gills during gradual adaptation to sea w ater. Glucose availability in gills increased as a result of both high er glycogenolysis and greater supply of exogeneous glucose. This gluco se was mainly used for increased glycolysis, providing the ATP needed to perform the hypo-osmoregulatory work occurring in gills during adap tation to sea water.