The Effect of Temperature Acclimation on Pathways of Glucose Metabolism in the Trout

In warm (15 °C) acclimated Salvelinus fontinalis, (i) the respiration of epaxial muscle homogenates was almost completely inhibited by iodoacetate; (ii) C14O2was incorporated primarily into positions 3, 4 of liver glycogen, and (iii) in vivo and in vitro glucose-1-C14metabolism was similar to that of glucose-6-C14. The results suggest a predominant participation of the Embden–Meyerhof path.In cold-acclimated (4 °C) trout, (i) the respiration of muscle homogenates was higher and less sensitive to iodoacetate; (ii) less of the C14O2incorporated into liver glycogen appeared in carbon atoms 3 and 4; (iii) there was a sharp discrimination between the metabolism of C1- and C6- labelled glucose; and (iv) acetate-1-C14oxidation was lower, but incorporation into fat was higher than in the warm-adapted fish. An activation of the pentose phosphate cycle in conjunction with a higher rate of fat synthesis during cold compensation could account for all of the foregoing data.