Oxidative phosphorylation and ultrastructural transformation in mitochondria in the intact ascites tumor cell

Abstract

We have examined the ultrastructure of mitochondria as it relates to energy metabolism in the intact cell. Oxidative phosphorylation was induced in ultrastructurally intact Ehrlich ascites tumor cells by rapidly generating intracellular adenosine diphosphate from endogenous adenosine triphosphate by the addition of 2-deoxyglucose. The occurrence of oxidative phosphorylation was ascertained indirectly by continuous and synchronous monitoring of respiratory rate, fluorescence of pyridine nucleotide, and 90 degrees light-scattering. Oxidative phosphorylation was confirmed by direct enzymatic analysis of intracellular adenine nucleotides and by determination of intracellular inorganic orthophosphate. Microsamples of cells rapidly fixed for electron microscopy revealed that, in addition to oxidative phosphorylation, an orthodox --> condensed ultrastructural transformation occurred in the mitochondria of all cells in less than 6 sec after the generation of adenosine diphosphate by 2-deoxyglucose. A 90 degrees light-scattering increase, which also occurs at this time, showed a t (1/2) of only 25 sec which agreed temporally with a slower orthodox --> maximally condensed mitochondrial transformation. Neither oxidative phosphorylation nor ultrastructural transformation could be initiated in mitochondria in intact cells by the intracellular generation of adenosine diphosphate in the presence of uncouplers of oxidative phosphorylation. Partial and complete inhibition of oxidative phosphorylation by oligomycin resulted in a positive relationship to partial and complete inhibition of 2-deoxyglucose-induced ultrastructural transformation in the mitochondria in these cells. The data presented reveal that an orthodox --> condensed ultrastructural transformation is linked to induced oxidative phosphorylation in mitochondria in the intact ascites tumor cell.