Charakteristische Stoffwechselunterschiede zwischen Geweben homoiothermer und poikilothermer Tiere

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Abstract
Tissue respiration of the liver from homoiothermic (mouse, rat, guinea pig) and poikilothermic animals (toad, frog) was studied in the temperature range between 17.5 and 42.5[degree]C under the influence of 4,6-dinitro-o-cresol. The percentage activity of the O2 use of mammalian liver under dinitro-o-cresol decreased with rise in temperature whereas the O2 use of amphibian liver, under the same conditions, showed a decrease at lower temperatures, and an activation at higher temperatures. Changes in the respiratory decline in vitro and the activation energies (H) of respiration of the tissue under dinitro-o-cresol reveal characteristic differences between the tissue relatives of both groups of organisms. The results were interpreted according to Johnson''s theory which assumes a reversible equilibrium between active and inactive enzyme proteins in the cell. In the liver of poikilothermic animals the equilibrium appears to be shifted toward the inactive side, whereas in the liver of homoiothermic animals an extreme shift toward the active side can be assumed. An extension of the Johnson theory to a steady state kinetic would make it possible to explain the maxima in the percentage activity of tissue respiration occurring under the influence of dinitrocresol.