title: Oxidative energy metabolism in germ-free and conventional rat liver mitochondria.
abstract: The ADP:O ratios and State 3 (ADP-stimulated) and State 4 (controlled) rates of succinate, beta-hydroxybutyrate, isocitrate, glutamate, pyruvate + malate, alpha-ketoglutarate, and ascorbate + N,N,N',N'-tetramethylphenylenediamine (TMPD) oxidation were examined in liver mitochondria from germ-free and conventional rats of both Lobund Wistar (100-day-old) and Fisher (120-day-old) strains. The State 3 respiration rates of isolated mitochondria from germ-free and conventional rats were comparable except for the rate of succinate oxidation in the Wistar rats, which was significantly lower (approx. 10%). The State 4 respiration rates were generally lower in mitochondria isolated from germ-free Fisher rats (approx. 8%) and significantly lower (approx. 18%) in germ-free Wistar rats. The ADP:O ratios were similar in germ-free and conventional rats. Serum thyroxine concentrations indicated delayed maturation of thyroid function in young germ-free rats, but adult animals had concentrations similar to those found in conventional rats. The results indicate that, although absence of a microflora results in a 20-30% reduction in metabolic rate, the germ-free state has little influence on the functional respiration or oxidative phosphorylation of mitochondria isolated from the liver of the adult rat.
mesh_terms: D000244:Adenosine Diphosphate / Q000378:metabolism; D000818:Animals; D001205:Ascorbic Acid / Q000378:metabolism; D001835:Body Weight; D004734:Energy Metabolism; D005856:Germ-Free Life; D005971:Glutamates / Q000378:metabolism; D005993:Glycerolphosphate Dehydrogenase / Q000378:metabolism; D006885:Hydroxybutyrates / Q000378:metabolism; D007523:Isocitrates / Q000378:metabolism; D007656:Ketoglutaric Acids / Q000378:metabolism; D008099:Liver / Q000033:anatomy & histology; D008293:Malates / Q000378:metabolism; D008297:Male; D008930:Mitochondria, Liver / Q000201:enzymology / Q000378:metabolism*; D009929:Organ Size; D010085:Oxidative Phosphorylation; D010101:Oxygen Consumption; D010655:Phenylenediamines / Q000378:metabolism; D011773:Pyruvates / Q000378:metabolism; D051381:Rats; D013386:Succinates / Q000378:metabolism; D013974:Thyroxine / Q000097:blood
chemical_list: D005971:Glutamates; D006885:Hydroxybutyrates; D007523:Isocitrates; D007656:Ketoglutaric Acids; D008293:Malates; D010655:Phenylenediamines; D011773:Pyruvates; D013386:Succinates; D000244:Adenosine Diphosphate; D005993:Glycerolphosphate Dehydrogenase; D001205:Ascorbic Acid; D013974:Thyroxine