THE EFFECT OF TEMPERATURE ACCLIMATION ON PATHWAYS OF GLUCOSE METABOLISM IN THE TROUT

Abstract

In warm (15 °C) acclimated Salvelinus fontinalis, (i) the respiration of epaxial muscle homogenates was almost completely inhibited by iodoacetate; (ii) C 14 O 2 was incorporated primarily into positions 3, 4 of liver glycogen, and (iii) in vivo and in vitro glucose-1-C 14 metabolism was similar to that of glucose-6-C 14 . 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 C 14 O 2 incorporated 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-C 14 oxidation 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.