Publication

Ethanol Formation and pH-Regulation in Fish

van Waarde, A., Van den Thillart, G. & Verhagen, M. 1993 Surviving Hypoxia: Mechanisms of Control and Adaptation. Hochachka, P. W., Lutz, P. L., Sick, T., Rosenthal, M. & van den Thillart, G. (eds.). Boca Raton: CRC Press, p. 157-170 14 p. 11

Research output: Chapter in Book/Report/Conference proceedingChapter

Three fish species (goldfish, crucian carp, and bitterling which all belong to the Cyprinid family) produce ethanol, CO2, and ammonia during environmental anoxia. Ethanol is formed in the myotomal muscles by the concerted action of mitochondrial pyruvate decarboxylase and cytosolic alcohol dehydrogenase. The activity of alcohol dehydrogenase is at least 100-fold higher than that of pyruvate decarboxylase to prevent accumulation of toxic acetaldehyde. Experiments with isolated mitochondria and metabolite assays in intact fish indicate that pyruvate is quantitatively converted to ethanol and lactate in the absence of oxygen, whereas the decarboxylation rate is allosterically regulated by the concentration of inorganic phosphate and the intracellular pH. Activation of pyruvate decarboxylase by H+ may cause the ethanol pathway to function as a pH-stat which prevents a fall of pH below 6.9. Measurements of substrate degradation (glycogen, nucleotides, free amino acids) and end product accumulation (carbon dioxide, lactate, ethanol, ammonia) in anoxic fish suggest that the carbon skeletons of ethanol and lactate are derived from glycogen stores in muscle and liver, whereas ammonia may originate from whole body nucleotides and myotomal glutamine. Glycogenolysis is more than sufficient to account for the anaerobic ethanol excretion, and previous reports which suggested an additional source of carbon are shown to be in error.
Original languageEnglish
Title of host publicationSurviving Hypoxia
Subtitle of host publicationMechanisms of Control and Adaptation
EditorsPeter W Hochachka, P.L. Lutz, T. Sick, M. Rosenthal, G. van den Thillart
Place of PublicationBoca Raton
PublisherCRC Press
Pages157-170
Number of pages14
ISBN (Print)0-8493-4226-0
StatePublished - 1993
Externally publishedYes

    Keywords

  • acid-base equilibrium

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