title: Ceramide interaction with the respiratory chain of heart mitochondria.
abstract: A study is presented on the interaction of ceramide with the respiratory chain of rat heart mitochondria, and a comparison is made between the effects elicited by short- and long-chain ceramides. N-Acetylsphingosine (C(2)-ceramide) and N-palmitoylsphingosine (C(16)-ceramide) inhibited to the same extent the pyruvate+malate-dependent oxygen consumption. Succinate-supported respiration was also inhibited by ceramides, but this activity was substantially restored upon the addition of cytochrome c, which, on the contrary, was ineffective toward the ceramide-inhibited NADH-linked substrate oxidation. Direct measurements showed that short- and long-chain ceramides caused a large release of cytochrome c from mitochondria. The ceramide-dependent inhibition of pyruvate+malate and succinate oxidation caused reactive oxygen species to be produced at the level of either complex I or complex III. The activity of the cytochrome c oxidase, measured as ascorbate/TMPD oxidase activity, was significantly stimulated and inhibited by C(2)- and C(16)-ceramide, respectively. Similar effects were observed on the activity of the individual respiratory complexes isolated from bovine heart. Short- and long-chain ceramides had definitely different effects on the mitochondrial membrane potential. C(2)-ceramide caused an almost complete collapse of the respiration-dependent membrane potential, whereas C(16)-ceramide had a negligible effect. Similar results were obtained when the potential was generated in liposome-reconstituted complex III respiring at the steady-state. Furthermore, C(2)-ceramide caused a drop of the membrane potential generated by ATP hydrolysis instead of respiration, whereas C(16)-ceramide did not. Finally, only short-chain ceramides inhibited markedly the reactive oxygen species generation associated with membrane potential-dependent reverse electron flow from succinate to complex I. The emerging indication is that the short-chain ceramide-dependent collapse of membrane potential is a consequence of their ability to perturb the membrane structure, leading to an unspecific increase of its permeability.
authors.affiliation: Department of Medical Biochemistry and Biology and Centre for the Study of Mitochondria and Energy Metabolism (CNR), University of Bari, 70124 Bari, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Di Paola
authors.forename: T
authors.initials: T
authors.lastname: Cocco
authors.forename: M
authors.initials: M
authors.lastname: Lorusso
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D002417:Cattle; D002518:Ceramides / Q000737:chemistry / Q000494:pharmacology*; D003574:Cytochrome c Group / Q000494:pharmacology; D004579:Electron Transport / Q000187:drug effects*; D003576:Electron Transport Complex IV / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000378:metabolism; D008081:Liposomes / Q000378:metabolism; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects; D008929:Mitochondria, Heart / Q000187:drug effects / Q000378:metabolism*; D009097:Multienzyme Complexes / Q000378:metabolism; D009243:NAD / Q000378:metabolism; D010084:Oxidation-Reduction; D010101:Oxygen Consumption / Q000187:drug effects; D051381:Rats; D017208:Rats, Wistar
chemical_list: D002518:Ceramides; D003574:Cytochrome c Group; D008081:Liposomes; D009097:Multienzyme Complexes; D009243:NAD; D000255:Adenosine Triphosphate; D006861:Hydrogen Peroxide; D003576:Electron Transport Complex IV