NUCLEOTIDES AND MITOCHONDRIAL FUNCTION 239 



References 



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19. Klingenberg, M., and Schollmeyer, P. (in preparation). 



Discussion 



Slater : Alay I take up the point we were discussing with Dr. Chance a moment 

 ago. You require ATP for the reduction of succinate in your freshly prepared rat- 

 skeletal-muscle sarcosomes, but when they are treated with albumin ATP is no 

 longer required. You suggest that the albumin removes an uncoupler. Now Dr. 

 Chance's pigeon-heart sarcosomes require ATP and our rabbit-heart sarcosomes 

 do not require ATP. The difference between Dr. Chance's results and ours could 

 then be explained by Dr. Klingenberg by the presence or absence of an uncoupler 

 whereas Dr. Chance would prefer to explain it by the absence or presence of endo- 

 genous substrate. Is it possible, then, that albumin is removing an endogenous 

 substrate which is a fatty acid rather than an uncoupler ? 



Klingenberg : I would say that albumin removes the uncoupler or may pre- 

 serve endogenous substrate because ATP is no longer required. 



Chance: I would be inclined to agree with Dr. Klingenberg's view that we 

 either add or preserve the endogenous substrate so that energy would be available, 

 however, for the reduction of the pyridine nucleotide on addition of Dc-glycero- 

 phosphate or succinate. 



Slater : I thought you said that albumin was removing an uncoupler. 



Klingenberg : The general opinion is that it removes an uncoupler. 



Chance : You can remove an uncoupler by ATP. 



Klingenberg: I presume that skeletal muscle mitochondria are slightly 

 uncoupled and also have in the presence of endogenous substrate a rather low level 

 of ATP or high energy substances. 



Slater: Have you in mind as an uncoupler the unsaturated fatty acids ? 



Klingenberg : Possibly. 



Chance : What is the effect of ATP when you have added glycerophosphate to 

 the skeletal muscle but not phosphate or ADP ? 



