VARIATIONS IN TISSUE RESERVES, PLASMA METABOLITES AND PANCREATIC HORMONES DURING FASTING IN IMMATURE CARP (CYPRINUS-CARPIO)

1. Immature carp were subjected to 2-month fasting periods. Mobilization of reserves in liver and muscle, and the energy contribution of each reserve were studied. Changes in plasma glucose, amino acids, insulin and glucagon levels were determined throughout the experiment. 2. No changes were observed in plasma glucose, insulin or glucagon at 19 days of fasting, but plasma amino acids increased. At 50 days of fasting, both plasma glucagon and amino acids increased, liver glycogen decreased and muscle proteolysis began. 3. Between 50 and 67 days of fasting, plasma glucose and insulin decreased significantly, while glucagon and amino acids continued to increase. Strong muscular proteolysis was observed while liver glycogen stabilized. 4. The contribution of each reserve in liver and muscle to energy production throughout fasting is considered.