174 T. E. CONOVER 



naturally-occurring quinones of a similar type might serve in a similar 

 role in the intact cell. 



It was observed by Ernster [7] that there was in liver slices an Amytal- 

 resistant respiration which amounted to about 30-40°,, of the total ob- 

 served respiration with glucose as substrate (Fig. 3). This is in contrast 

 to the more recent report of Chance and Hess [i] with ascites tumour cells 

 where the respiration was completely inhibited by Amytal. Investigations 

 were initiated by Mr. Kadenbach in this laboratory on the nature of this 

 Amytal-resistant respiration with particular emphasis on whether DT 

 diaphorase might be involved. 



10- 



6- 



D no add itions 

 Q Vit,K3-b:sultit( 



i 



/ / 



12 



10 



D no addit ions 

 S dicoumarol 



none Amytal 



none Amytal 



Fig. 4. The effect of vitamin K3 and dicoumarol on the respiration of liver 

 slices in the presence and absence of Amytal. Each Warburg vessel contained 50 

 /limoles glucose, 100 mg. wet weight rat liver slices, and o-8 ml. Krebs-Ringer- 

 phosphate solution containing half the usual concentration of CaCl,. The amounts 

 of the additions were 2 jumoles Amytal, 10"'- /itmole vitamin Kg-bisulphite, and 

 2 X io~- ^mole dicoumarol. The final volume was i o ml. Gas phase, oxygen. 

 Temperature, 37 "5 . Time measured, 60 min. 



Preliminary investigation quickly showed that the function of DT 

 diaphorase in either the normal or the Amvtal-resistant respiration of rat 

 liver slices with glucose as substrate would be difficult to demonstrate. 

 Figure 4 shows in a simple manner two experiments in which the addition 

 of vitamin K.j-bisulphite had no stimulatory effect on either normal or 

 Amytal-resistant respiration, nor did addition of dicoumarol show any 

 inhibitory effect on respiration in these two conditions. 



The water-soluble vitamin Kg-bisulphite was used in these experi- 

 ments in order to avoid addition of alcohol to the system, since alcohol is 



