Glycolytic function in goldfish hepatocytes at different temperatures: relevance for Na+ pump activity and protein synthesis.

Abstract

ABSTRACT Cellular metabolism of ectotherms may respond to temperature changes with a shift in the choice of substrate preferentially catabolized for ATP production (Johnston and Dunn, 1987). This has been shown in acclimated fish, in which a temperature-dependent switch from carbohydrates as the main fuel for energy metabolism to other fuels, or vice versa, can occur. Such shifts help to indicate the relative importance of aerobic glycolysis as an ATP-supplying process. The preferred energy source at a given temperature depends upon the temperature range investigated, as well as on the species, on the tissue and upon nutritional factors. The adaptive significance of shifts between energy sources is not always clear. While in some cases ecological arguments may provide plausible explanations (e.g. seasonal adaptation to migration and reproductive requirements; Stone and Sidell, 1981; Moerland and Sidell, 1981), evidence is accumulating that structural or functional features inherent in the metabolic organisation of the cell may also play a role in determining the nature of such responses (Sidell, 1983; Sidell and Hazel, 1987). Of particular relevance in this respect is the interaction between diffusional flux and the rate of enzymatic activity in shaping specific temperature effects on cellular metabolism.