Ascorbate and Fe++-induced lipid peroxidation in liver mitochondria isolated from copper-deficient rats

The effects of ascorbate and Fe++ on lipid peroxidation are compared in liver mitochondria isolated from control and copper-deficient rats. Spontaneous, Fe++- and ascorbate-induced formation of compounds reacting with the thiobarbituric acid (TBA) and the swelling in the mitochondria are studied as indicators of lipid peroxidation. The initial level of TBA-reacting compounds in freshly isolated copper-deficient mitochondria is higher than that in the control mitochonidria. Incubation at 20--22 degrees C for 60 min leads to a greater increase in the amount of the spontaneously formed TBA-reacting compounds in the copper-deficient mitochondria. Both the Fe++--ions and the ascorbate induce lipid peroxidation more intensively in the copper-deficient mitochondria than in the controls. The differences between the two types of mitochondria are manifested also with respect to the effect of antimycin A on the ascorbate-induced lipid peroxidation. The data obtained concerning a more enhanced spontaneous and induced lipid peroxidation in copper-deficient mitochondria are explained with the higher level of lipid peroxides, changes organization and fatty-acid composition of the membranes, and with lower activity of superoxide dismutase and catalase.