Levels of cytochr­omes in rat rat mitochondria during post-natal development

A. B. CHEPELINSKY; G. RODRÍGUEZ DE LORES ARNAIZ

BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES

ELSEVIER SCIENCE BV

Año: 1970 vol. 197 p. 321 - 323

0005-2736

Several aspects of mitochondrial metabolism during brain maturation have been described, however the pattern of changes of the different components of the respiratory chain have not yet been studied. In the present communication the changes in the levels of cytochromes and ubiquinone in purified mitochondria at different stages of development are reported. For the preparation of brain mitochondria groups of 15-45 Wistar rats of either sex at various ages were used. Purified mitochondria were isolated from whole brain by the method of Lovtrup and Zelander. Cytochrome measurements were made by using a Chance wavelength scanning recording spectrophotometer 5 constructed in the Johnson Foundation, Philadelphia, Pa. For the assay of cytochromes cuvettes contained in final concentration: 10 mM phosphate buffer (pH 7.4), 0.22 M sucrose and rat-brain mitochondria (1.5-3 mg protein per ml); to one of the cuvettes, succinate was added to achieve 10 mM and the difference spectrum was recorded after becoming anaerobic. A similar schedule was followed for cytochrome b except that together with succinate, antimycin A (Sigma Chem. Co., Type III) was added to achieve a final concentration of 0.44 microgram/ml; mitochondrial protein was 3-4 mg/ml. The millimolar extinction coefficients for cytochromes were used. The results were expressed as nmoles/mg protein.