| Abstract: | Abstract— Data on the metabolic characteristics of mitochondria from rabbit brain have been obtained using low concentrations (100–300 μm) of 14C-labelled substrates of the Krebs tricarboxylic acid cycle. Oxygen consumption was measured polarographically with a Clark-type electrode. Products of the reactions were separated by chromatography on Dowex-1 columns. Data are reported for relative respiratory quotients of various substrates, respiratory control ratios, accumulation of 14C in various tricarboxylic acid cycle intermediates and the effect of malate and several inhibitors on these parameters. The data have been compared with similar experiments on mitochondria from rabbit heart. Mitochondria from rabbit brain differ substantially from heart mitochondria: those from brain have a very low capacity for oxidation of acetate and other short chain fatty acids; they do not form j3-hydroxybutyrate; they produce substantial amounts of α-ketoglutarate and require added dicarboxylic acid to yield a maximum respiratory quotient. Like those from heart, brain mitochondria have a high capacity for pyruvate oxidation and a low Km for this substrate. The results have been discussed and compared with work reported by other investigators. |
