title: Cytoplasmic cellular structures control permeability of outer mitochondrial membrane for ADP and oxidative phosphorylation in rat liver cells.
abstract: The kinetics of regulation mitochondrial respiration by external ADP in permeabilized hepatocytes was studied further. In digitonin-permeabilized hepatocytes, the apparent Km for ADP in regulation of respiration was decreased from 275 +/- 35 microM in control to 48 +/- 8 microM by a treatment with trypsin (15 min, 0.125 mg/ml). In liver tissue homogenates, trypsin treatment similarly decreased the Km value for ADP. These results show that ADP diffusion in hepatocytes may be retarded due to some unknown cytoplasmic trypsin-sensitive protein factor(s) which may be lost during isolation of mitochondria. Since we have previously reported a limited permeability of the outer mitochondrial membrane in isolated hepatocytes (Saks et al. 1995, Biochem. Biophys. Res. Commun., 208, 919-926), we conclude that an important site of control of respiration in liver cells in vivo is located at the porin channels of the outer mitochondrial membrane.
authors.affiliation: Laboratoire de Bioénergétique, Université Joseph Fourier, Grenoble, France.
authors.forename: E M
authors.initials: EM
authors.lastname: Fontaine
authors.forename: C
authors.initials: C
authors.lastname: Keriel
authors.forename: S
authors.initials: S
authors.lastname: Lantuejoul
authors.forename: M
authors.initials: M
authors.lastname: Rigoulet
authors.forename: X M
authors.initials: XM
authors.lastname: Leverve
authors.forename: V A
authors.initials: VA
authors.lastname: Saks
mesh_terms: D000244:Adenosine Diphosphate / Q000378:metabolism*; D000818:Animals; D002478:Cells, Cultured; D003593:Cytoplasm / Q000378:metabolism / Q000648:ultrastructure; D007425:Intracellular Membranes / Q000378:metabolism* / Q000648:ultrastructure; D007700:Kinetics; D008099:Liver / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D008854:Microscopy, Electron; D008930:Mitochondria, Liver / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D010085:Oxidative Phosphorylation; D010101:Oxygen Consumption; D010539:Permeability; D051381:Rats; D014357:Trypsin / Q000494:pharmacology
chemical_list: D000244:Adenosine Diphosphate; D014357:Trypsin