Turnover rates of glucose and lactate in rainbow trout during acute hypoxia

Turnover rates of glucose and lactate in trout during hypoxic exposure were undertaken to determine the rates of flux of these metabolites into and out of the blood. This measurement provides a more quantitative indication of rates of metabolite flux than do simple concentration values. Specific activity decay curves were obtained from control rainbow trout (Salmo gairdneri) plasma, and from trout subjected to 3 h of hypoxia. Glucose turnover remained constant at 10.7 μmol∙min−1∙kg−1, while lactate turnover increased from 2.8 ± 0.4 μmol∙min−1∙kg−1 to 20.6 ± 6.8 μmol∙min−1∙kg−1. It is argued that the increase in lactate turnover rate emphasizes the fact that anaerobic glycolysis is activated, and that the lack of increase in rates of glucose turnover provides evidence for endogenous fuel sources for glycolysis.