Development of NADH Oxidation by Red Beet Mitochondria on Slicing and Aging of The Tissues

Abstract

Mitochondria isolated from red beet slices that have been aged for 24 h or more develop a capacity to oxidize external NADH, with oxygen as the electron acceptor. This activity is not seen with mitochondria isolated from fresh tissue. The induced activity does not arise because an inhibitor is eliminated or an activator is developed during the aging process. Increased NADH dehydrogenase activity was found to be associated with both the outer and the inner membranes, but the NADH oxidation to oxygen was associated solely with the inner membrane. The induced NADH oxidation was insensitive to rotenone and coupled to two sites of phosphorylation. Mitochondria isolated from aged tissue also develop some alternative oxidase activity, as judged by antimycin a- and cyanideresistant malate oxidation, but t h ~iss less marked. The induced NADH oxidation develops in parallel with the induced respiration of the slices of tissue. In red beet slices, the 2,4-dinitrophenol-uncoupled respiration also increases during aging. An attempt is made to integrate the respiratory change of the mitochondria with those of the tissue.