Energy Pathways of Hepatoma No. 5123

Abstract

SINCE the original experiments of Warburg with slices of tumour there has been intense investigation of, and discussion about, a specific tumour energy metabolism^1,2. This concept, originally characterized by high rates of aerobic and anaerobic glycolysis, has been extended to include certain ancillary features: a moderate respiratory rate with minimal increase in respiration following the addition of succinate and other respiratory substrates³, a respiratory quotient (R.Q.) between 0.75 and 0.90 signifying a mixed protein, fat, carbohydrate respiratory substrate⁴, and a protein-synthesizing system which effectively incorporates amino-acid anaerobically if glucose is present⁵. Up to the present time the major exceptions to the concept of a specific tumour metabolism have been certain normal tissues (renal medulla, jejunal mucous membrane, myeloid bone marrow and retina) which share one or more of the characteristics of the tumour slice². Occasional mouse tumours have been observed which display active anaerobic glycolysis without aerobic glycolysis⁶, a finding which has been explained by the active respiratory rate and normal Pasteur effect of mouse tissues. The present communication is of particular interest because for the first time a rat tumour is described which displays very low rates of aerobic and anaerobic glycolysis.