Production of carbon dioxide and lactic acid from radioactive glucose by tissue in culture

Abstract Chick embryo mesenchyma tissue in culture (mostly monolayers with known numbers of cells) was incubated in growth-promoting nutrient media with radioactive glucose, the carbon dioxide and the lactic acid isolated, and their radioactivities determined with the gas Geiger counter. Both “synthetic” and “natural” media were used. Some experiments were also done with tissue kept in salt solution. As the number of cells per unit quantity of glucose increases, glycolysis per cell decreases and respiration per cell increases, as far as glucose serves as the substrate. Thus the Crabtree effect in tissue culture is at least partly due to a switch from the utilization of glucose by respiration to its utilization by glycolysis (“one-substrate” theory). The effects of controlled damage by trypsin resemble those of an increase in the supply of glucose. In all experiments with growth-promoting media more glucose is glycolyzed than respired, but more free energy is usually derived from respiration than from glycolysis. The total amount of free energy derived from glucose, per cell, does not change significantly as the supply of glucose per cell is varied. No major differences in the utilization of glucose are observed in the given conditions between monolayers and solid tissue pieces.