Glycolysis and the Pasteur Effect 209 



should we say exclusion : the rate of either aerobic or anaerobic 

 glycolysis in intact ascites tumour cells is not limited by the 

 capacities of the glycolytic enzymes. 



Let us turn now to what we call studies of intact cells. We 

 have tried to investigate cellular metabolism by allowing 

 ascites cells to utilize glucose under a variety of conditions. 

 After short time intervals, the metabolic process was inter- 

 rupted, e.g., with perchloric acid, and the concentrations of 

 adenine nucleotides, intermediates, phosphate, etc., were 

 determined in the extract. We realize fully that this experi- 

 mental approach is not an ideal one, but unfortunately it is 

 the only one available at present for studying most of the 

 intracellular components. Let us remain cognizant of the fact 

 that by turning from studies with extracts to "intact cells", 

 we have but delayed the process of producing artifacts which 

 we believe are inseparably attached to any procedure involving 

 the disruption of the cell structure. But at least we produce 

 by this approach an artifact of another kind, and the know- 

 ledge we obtain bears perhaps a closer relationship to cellular 

 metabolism than that derived from studies with extracts. 

 We can but hope that by collecting data from a large variety 

 of artifacts we shall be able to extract the information 

 necessary to obtain a composite picture of intracellular meta- 

 bolism. Table III will serve to illustrate what information we 

 attempt to obtain from such an approach. 



Table III 



Rate of glycolysis and intracellular phosphate 

 and adp levels 



Incubation was made in Warburg vessels at 30 °C for 40 minutes. Results 

 are expressed as [jLmoles/140 mg. protein. 



