The extent of ADP.Fe/NADPH-induced lipid peroxidation measured as production of thiobarbituric acid-reactive substances (TBARS) was determined in isolated membranes from cerebral cortex, heart and kidney of 21-days- old rats. The time course of lipid peroxidation showed higher production of TBARS in cerebral cortex than in heart and kidney. Our data indicate that high level of TBARS production is not due to high activity of NADPH oxidoreductase but due to high content of endogenous lipids in cerebral cortex membranes that could be modified. Higher production of TBARS in cerebral cortex is the result of higher content of lipids in cerebral cortex membranes because NADPH cytochrome c reductase activity in membranes of cerebral cortex is lower than that of heart and kidney.
Mitochondria were isolated from regenerating rat liver 12, 24 and 48 h after partial hepatectomy. The "State 3" and "State 4" respiration were measured in the presence of succinate. The P/O quotient and respiratory control index (RCI) were calculated. The experimental data showed that the partial uncoupling of oxidative phosphorylation in regenerating liver mitochondria occurring in the early period of regeneration is partly due to free fatty acids.
Glycerol-3-phosphate oxidation in brown adipose tissue mitochondria of cold-adapted hamster is strongly inhibited by phospholipase A2 (PLA2)- Our data show that the glycerol-3-phosphate branch of the respiratory chain is sensitive to PLA2 action more than the succinate branch and that the transfer of reducing equivalents from the glycerol-3-phosphate dehydrogenase to arteficial electron acceptor is especially sensitive to the PLA2 action.
The recovery of total DNA content and recovery of total cytochrome c oxidase activity in the rat liver after partial hepatectomy is accelerated by triiodothyronine applied in three doses, two before and one immediately after liver resection. Triiodothyronine-treated animals already have higher cytochrome c oxidase activity before resection. The recovery of the tissue oxidative capacity after partial hepatectomy is more rapid in triiodothyronine-treated animals. These data indicate that hormonal activation of the liver regeneration process is involved.
Aging is a process drawing attention of many researchers, and at present many theories exists, which try to explain this chain of inevitable events leading to death of organism. In this article we focused our attention on a theory explaining the degenerative changes occurring during aging by the effect of oxygen free radicals. These highly reactive radicals are produced during oxidative phosphorylation in mitochondria. All cellular components appear to be sensitive to oxygen-radical damage. Lipids, proteins and nucleic acids are probably the most susceptible to this injury. Lipoperoxidation of lipids together with cross-linking of proteins with phospholipids and nucleic acids caused changes in membrane fluidity. Mitochondrial DNA coding several subunits of respiratory chain enzymes can be also damaged by these radicals. All these changes together have negative impact on mitochondrial metabolism resulting progressive decrease of the efficiency of oxidative phosphorylation and thus of the whole organism.