1. Changes in the concentrations of respiratory components, phosphorylative activity, the cytochrome oxidase activity of mitochondria and the hepatic adenylate energy charge level (in situ) were studied in cirrhotic rat liver induced by carbon tetrachloride (CCl4).
2. In the cirrhotic liver mitochondria, concentrations of cytochrome a(+ a3), cytochrome b, coenzyme Q9 and coenzyme Q10 increased significantly to 2.44 ± 0.02 × 10−10 (mean ± se), 1.37 ± 0.05 × 10−10, 25.57 ± 0.47 × 10−10 and 5.39 ± 0.26 × 10−10 mol/mg of mitochondrial protein, respectively, compared with 1.83 ± 0.03 × 10−10, 1.22 ± 0.02 × 10−10, 16.24 ± 0.39 × 10−10 and 1·81 ± 0.07 × 10−10 in normal rats [P < 0.001 for cytochrome a(+ a3), coenzyme Q9 and coenzyme Q10, and P < 0.01 for cytochrome b].
3. Concentrations of flavoprotein and pyridine nucleotides decreased significantly to 13.33 ± 0.14 × 10−10 and 45.68 ± 1.59 × 10−10 mol/mg of mitochondrial protein, respectively, compared with 14.79 ± 0.33 × 10−10 and 86.26 ± 1.83 × 10−10 in normal rats (P < 0.001). There was no significant difference in the concentration of cytochrome c(+ c1).
4. Cytochrome oxidase activity per unit of cytochrome a(+ a3) increased significantly to 67.43 ± 1.71 atoms O s−1 mol−1, compared with 55.77 ± 1.16 in normal rats (P < 0.001). By contrast, phosphorylative activity per unit of cytochrome a(+ a3) decreased significantly in the cirrhotic liver to 10.40 ± 0.36 s−1 compared with 13.43 ± 0.49 in normal rats (P < 0.001). The total adenine nucleotide concentration and the hepatic energy charge level decreased significantly in the cirrhotic liver to 3.420 ± 0.075 μmol/g of wet liver and 0.806 ± 0.003, respectively, compared with 3·854 ± 0.088 and 0.841 ± 0.004 in normal rats (P < 0.001).
5. It is concluded that in mitochondria obtained from CCl4-induced cirrhotic rat liver in which the energy charge level is decreased, cytochrome oxidase activity per unit of cytochrome a(+ a3) is increased in association with an increase in cytochrome a(+ a3) concentration.
