Utilization of the Ethanol Pathway in Carp Following Exposure to Anoxia

1. Crucian carp (Carassius carassius L.) and Common carp (Cyprinus carpio L.) were subjected to 2h progressive hypoxia followed by up to 6 h anoxia in closed respirometers at 15°C. 2. The concentrations of glycogen, glucose, phosphoryl creatine, alanine, succinate, lactate, ethanol and ammonia were determined in whole Crucian carp following exposure to both hypoxia and anoxia. 3. Ethanol and lactate were the main anaerobic end products. Glycogen utilization during anoxia amounted to 2mmol glucose equivalents.kg wet weight−1 h−1. Around 85% of the ethanol produced (2.8mmolkg−1h−1) was excreted. Lactate accumulation (0.7 mmol kg−1 h−1) was only sufficient to account for 18.5% of the glycogen stores utilized. Ammonia production(0.2 mmol.kg body wt−1 h−1) was independent of the environmental oxygen availability. 4. Ethanol concentrations (μmol.g wetwt−1) were 7 in red myotomal muscle, 4 in white myotomal muscle, and 2 in liver after 6h anoxia. 5. In contrast to Crucian carp, Common carp (Cyprinus carpio L.) did not produce ethanol at 15°C even after near lethal exposure to anoxia (5–6 h).