. Discussion 227 



cells as compared to normal cells. This reminds me of the story of what 

 happened on one June 21st: One young lady whose nationality shall 

 remain undisclosed turned to the young man and said, "Do you realize 

 that this is the longest day in the year?", while the French girl turned 

 to her young man and said, "Do you realize that this is the shortest 

 night of the year? " 



To come back to serious matters, I would like to point out that 

 irrespective of which view one subscribes to, the nriajor fact is that 

 tumour cells produce a large amount of lactic acid under aerobic 

 conditions. I feel that this fact by itself must have a very pronounced 

 influence on the whole metabolic machinery of the cell. I would not be 

 surprised if these changes in intracellular pH have a tremendous effect 

 on the entire metabolism and physiology of the cell. 



Greville: This, of course, is a 30-year-old controversy; but, in general, 

 non-malignant cells have an anaerobic glycolysis more commensurate 

 with their respiration than do tumour cells. Is there not a basic dis- 

 parity between the anaerobic glycolysis and respiration in most tumour 

 cells? In other words, in malignant cells a small respiration is trying to 

 cope with a big anaerobic glycolysis. 



Backer: I believe that this is true for most tissues, but what about 

 brain tissue and yeast cells which have a very high anaerobic glycolysis? 



Mcllwain: From this point of view, certain cerebral tumours do 

 follow the pattern of tumours from other tissues. They show greater 

 aerobic glycolysis than do normal cerebral tissues. 



Chance: The ascites tumour cell has the same cytochrome content 

 as the liver cell. 



Lehninger : Dr. Racker, on the question of identity of the inorganic 

 phosphate that you measure, is that really inorganic phosphate? 

 Some of it might be a very labile phosphate ester. 



Racker: Prof. Lynen pointed out many years ago that the chemical 

 analysis of the intracellular inorganic phosphate might include some 

 acid-labile, high-energy phosphate compounds. We have not been able 

 to detect, at least in ascites tumour cells, significant amounts of acyl 

 phosphate. We therefore feel at the present time that we actually 

 measure intracellular inorganic phosphate by chemical analysis. It 

 just appears from the metabolic studies that some of this inorganic 

 phosphate is not available for glycolysis. 



Lynen : That is my idea too. Dr. Holzer, in my laboratory, tried to 

 detect acyl phosphate in intact yeast cells but could not find any. 



Hess: I think that a certain amount of the inorganic phosphate is 

 readily available in the mitochondria for respiration. As I have already 

 shown (Fig. 1, p. 126), a certain amount of inorganic phosphate is taken 

 up immediately in stoichiometric relationship to the oxygen uptake at 

 the same time after addition of glucose. It can be related to the P/O 

 ratio and is also in a relationship of 1/1 to the glucose consumed. This 

 store of inorganic phosphate is definitely limited by a minimal concen- 

 tration of approximately 6 [j.m phosphate /g. wet weight of ascites tumour 

 cells. There might be a difference between your experimental conditions 

 and ours. In this connexion, I would point out that in some of these 



