Studies on the swimming musculature of the rainbow trout.

Some aspects of anaerobic metabolism in the red and white (mosaic) muscles of the rainbow trout have been studied during environmental hypoxia. Evidence has been obtained for the operation of anaerobic pathways other than glycolysis, especially in the superficial red muscle. L-alanine and succinate were observed to accumulate as anaerobic endproducts in this tissue. Anaerobic glycolysis also increased significantly during hypoxia, but only in the white muscle. Glycogen stores were depleted by 70–85 % in both red and white muscle. Glucose increased in concentration in the red but not in the white muscle. In an attempt to understand some of the species differences in the susceptibility of fish to hypoxia the results of the present study have been compared with an earlier study on the carp (Johnston, 1975). The effect of death from hypoxia on the levels of muscle metabolites has also been studied.