Effects of glucagon on the redox states of cytochromes in mitochondria in situ in perfused rat liver.
The effects of glucagon on the respiratory function of mitochondria in situ were investigated in isolated perfused rat liver. Glucagon at the concentrations higher than 20 pM and cyclic AMP (75 microM) stimulated hepatic respiration, and shifted the redox state of pyridine nucleotide (NADH/NAD) in mitochondria in situ to a more reduced state as judged by organ fluorometry and beta-hydroxybutyrate/acetoacetate ratio. The organ spectrophotometric study revealed that glucagon and cyclic AMP induced the reduction of redox states of cytochromes a(a3), b and c+c1. Atractyloside (4 micrograms/ml) abolished the effects of glucagon on these parameters and gluconeogenesis from lactate. These observations suggest that glucagon increases the availability of substrates for mitochondrial respiration, and this alteration in mitochondrial function is crucial in enhancing gluconeogenesis.
D000818:Animals; D001278:Atractyloside / Q000494:pharmacology; D003573:Cytochrome b Group / Q000378:metabolism; D003574:Cytochrome c Group / Q000378:metabolism; D003580:Cytochromes / Q000378:metabolism*; D003575:Cytochromes c1 / Q000378:metabolism; D003576:Electron Transport Complex IV / Q000378:metabolism; D005934:Glucagon / Q000494:pharmacology*; D008297:Male; D008930:Mitochondria, Liver / Q000378:metabolism*; D009243:NAD / Q000378:metabolism; D010084:Oxidation-Reduction; D010101:Oxygen Consumption / Q000187:drug effects; D051381:Rats; D011919:Rats, Inbred Strains
D003573:Cytochrome b Group; D003574:Cytochrome c Group; D003580:Cytochromes; D009243:NAD; D001278:Atractyloside; D005934:Glucagon; D003575:Cytochromes c1; D003576:Electron Transport Complex IV