Substrate oxidation and energy production by Guerin epithelioma mitochondria

The mitochondria from Guerin epithelioma and normal rat liver were isolated and their energy production abilities were compared. Both mitochondrial preparations were of the same degree of purity. The percentage of mitochondrial protein in tumour homogenates was three times lower than in rat liver. Guerin epithelioma mitochondria characterized a high respiratory control ratio with succinate and low with NAD dependent substrates in the presence of ADP. The ADP-ATP exchange rate was five times lower in tumour than in rat liver. Energy dependent potassium ions accumulation was about 45% of that found in rat liver mitochondria. The uptake of respiratory substrates was similar in tumour and liver mitochondria. These results indicate on the low efficiency of oxidative phosphorylation in the mitochondria of Guerin epithelioma.