The metabolism of lactic and pyruvic acids in normal and tumour tissue

Publisher Website
Google Scholar
Abstract
Accurately reproducible results can be obtained with the Dixon-Keilin manometric apparatus when certain precautions are followed. In rabbit kidney cortex the course of the metabolism of lactate, pyruvate, succinate, fumarate, malate and oxaloacetate are followed by manometric measurements of O2 uptake, R. Q., and acid disappearance, and by chemical estimations of lactate, pyruvate and glycogen. A method is described for the determination of glycogen in dried tissue slices and medium. Kidney cortex oxidizes lactate slowly, pyruvate more rapidly, and the remaining substances still more rapidly with correspond- ing increases in the R. Q. Formate is not oxidized. Evidence shows that lactate is converted (reversibly) to pyruvate and pyruvate successively to succinate, malate, fumarate and oxaloacetate, the latter compound being finally decarboxylated to give pyruvic acid again in half the original amt. No glycogen synthesis occurs. Acetate is fairly rapidly oxidized, while [beta]-hydroxy-butyrate scarcely affects the respiration though there are indications that lactate as well as acetoacetate are formed from it. The normal respiration rate of minced tissue is reduced to about 1/6 the rate shown by thin slices, and all the mechanisms involved in the metabolism of the substances are inactivated except that the steps succinate [forward arrow] fumarate and fumarate [image] malate can still occur.