The Ratio β-Hydroxybutyric Acid/Acetoacetic Acid In the Blood under Various Experimental Conditions

Summary. The two components in the reversible reduction‐oxidation system, β‐hydroxybutyric acid/acetoacetic acid and their proportionate changes in the blood under experimental conditions have been examined: 1: in fasting humans after ingestion of glucose and during exercise. 2: in perfused liver‐ and muscle‐tissue of the cat. The pronounced variations in the reduction‐oxidation ratio of the ketone bodies in humans in these experiments might be explained by interaction between the β‐hydroxybutyric acid/acetoacetic acid system and the lactic acid/pyruvic acid system. In perfusion of liver‐ and muscle‐tissue reproducible changes take place in the reduction‐oxidation system of the ketone bodies, progressing with the duration of the perfusion. Attempts to influence on these changes by adding other reduction‐oxidation systems to the system of ketone bodies gave no indication of a reaction between the different systems. Unknown factors are still to be considered in the interpretation of in vitro experiments to the metabolism of the living cell.