170 A. L. SCHADE VOL. 12 (1953) 



genase was extracted in the first homogenization while the fresh cells still contained some 

 activity following the second homogenization. 



Aldolase levels were determined in the ascitic fluids of Krebs-2 ascites carcinoma 

 cell suspensions as they were removed fresh from the hosts and after the suspensions 

 were incubated in nitrogen and in oxygen. The results showed that the Krebs-2 tumor, 

 with respect to both the absolute levels of aldolase in the ascitic fluid and the heightened 

 levels in the anaerobically incubated aliquots, was similar to the Ehrlich ascites carci- 

 noma. The response of this tumor cell suspension to aerobic incubation also led to the 

 same conclusion. 



DISCUSSION 



The increase in concentration of aldolase, isomerase, and a-glycerophosphate de- 

 hydrogenase in the blood plasmas of both the albino C and dba strains of mice bearing 

 the Ehrlich carcinoma and thymoma ascitic tumors respectively is apparently a reflection 

 of the generally higher concentrations of these enzymes in the ascitic fluids associated 

 with the tumors growing as discrete cell suspensions in the peritoneal cavity of the hosts. 

 That the tumor cells serve; at least in part if not entirel}', as the source of these enzymes 

 appears probable since, as shown most readily with the Ehrlich and Krebs-2 carcinoma, 

 short time anaerobic in vitro incubation of the tumor cell suspensions led to greatly 

 increased enzyme concentrations in the ascitic fluids. As Warburg has pointed out'', 

 the in vivo conditions during the development of the Ehrlich ascites tumor are essentially 

 anaerobic as a consequence of the very high metabolic capacity of the tumor and the 

 relatively restricted supply of oxygen. 



Although the intracellular concentrations of these enzymes are many times those 

 found in the ascitic fluids and although the anaerobic conditions apparently obtaining 

 within the peritoneum are conducive to loss of some of these enzymes from the cells 

 to the ascitic fluid, it is improbable that their relatively high concentration in the fluid 

 is solely the result of passive loss from the tumor cells. We are led to consider the fact 

 that the dba thymoma, despite its relative refractivity to loss of these enz\'mes from its 

 cells to the ascitic fluid under in vitro anaerobic conditions, did show enzyme concentra- 

 tions in the ascitic fluid of the dba mouse 3 to 4 times as high as the Ehrlich ascites 

 carcinoma in the strain C albino mouse. That this observation derives from the behaviour 

 of the tumor rather than reflects a particular host response was demonstrated by our 

 injecting the Ehrlich ascites carcinoma into the dba strain mouse. The enzyme levels 

 in the blood plasma samples as well as in the ascitic fluids of the dba mice after appro- 

 priate intervals following inoculation were similar to those of the Ehrlich tumor in the 

 strain C albino host. 



ACKNOWLEDGEMENTS 



It is a pleasure gratefully to acknowledge the ever valuable collaboration of my 

 colleague, Dr. Hilton Levy, in this investigation. To Mr. Robert Reinhart and Mr. 

 Leroy Snellbaker I am indebted for their most helpful technical assistance. 



SUMMARY 



Otto Warburg's finding that the aldolase concentration in the ascitic fluid of the Ithrhch 

 ascites carcinoma increases significantly upon anaerobic in vitro incubation was confirmed, dba thy- 

 moma ascitic cell suspensions from dba mice were investigated under similar conditions and the ob- 



References p. lyi. 



