THE ACTION OF INSULIN ON THE METABOLISM OF CELL CULTURES

Abstract

SUMMARY 1. The effect of insulin on carbohydrate metabolism, nucleic acid synthesis and the incorporation of inorganic phosphate into cultured mammalian cells was investigated. 2. Insulin was always found to stimulate glycolysis. It also accelerated the utilization of pyruvic acid from the medium. 3. Enhanced turnover of phosphate in the acid-soluble and lipid fractions of the cells was found. Only rarely was there increased turnover of RNA phosphorus or DNA phosphorus, even in the presence of other phenomena. 4. Increased 32 P incorporation into acid-soluble compounds was observed in many experiments, it was not confined to energy-rich compounds. 5. Increased cell membrane activity was noted and this was often accompanied by increased visible pinocytosis. 6. It is concluded that most of the phenomena observed on treating cultured cells with insulin can be explained as being secondary to increased glycolysis. Increased pinocytosis may be a primary or secondary phenomenon in the chain of events.