Impact on energy metabolism of quantitative and functional cyclosporine-induced damage of kidney mitochondria.
In this study we have measured, under experimental conditions which maintained efficient coupling, respiratory intensity, respiratory control, oxidative phosphorylation capacity and protonmotive force. Succinate cytochrome-c reductase and cytochrome-c oxidase activities were also studied. These investigations were carried out using kidney mitochondria from cyclosporine-treated rats (in vivo studies) and from untreated rats in the presence of cyclosporine (in vitro studies). Inhibition of respiratory intensity by cyclosporine did not exceed 21.1% in vitro and 15.9% in vivo. Since there was no in vitro inhibition of succinate cytochrome-c reductase and cytochrome-c oxidase activities, the slowing of electron flow observed can be interpreted as a consequence of an effect produced by cyclosporine between cytochromes b and c1. Cyclosporine had no effect on respiratory control either in vitro or in vivo. Statistically significant inhibition of the oxidative phosphorylation was observed both in vitro (6.6%) and in vivo (12.1%). Moreover, cyclosporine did not induce any change of membrane potential either in vivo or in vitro. Our findings show that cyclosporine is neither a protonophore, nor a potassium ionophore. In cyclosporine-treated rats we notices a decrease of protein in subcellular fraction, including the mitochondrial fraction. The role of the inhibition respiratory characteristics by cyclosporine in nephrotoxicity in vivo must take account of these two parameters: inhibition of the respiratory characteristics measured in vitro and diminution of mitochondrial protein in cyclosporine-treated rats.
Aupetit
B
B
Service de Biochimie Médicale, Faculté de Médecine Pitié-Salpétrière, Paris, France.
Ghazi
A
A
Blanchouin
N
N
Toury
R
R
Shechter
E
E
Legrand
J C
JC
D000818:Animals; D003524:Cyclosporins / Q000494:pharmacology* / Q000633:toxicity; D004563:Electrochemistry; D004579:Electron Transport / Q000187:drug effects; D003576:Electron Transport Complex IV / Q000037:antagonists & inhibitors; D004734:Energy Metabolism / Q000187:drug effects*; D007668:Kidney / Q000378:metabolism / Q000648:ultrastructure*; D007674:Kidney Diseases / Q000139:chemically induced; D008297:Male; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism*; D010085:Oxidative Phosphorylation / Q000187:drug effects; D010101:Oxygen Consumption / Q000187:drug effects; D011522:Protons; D051381:Rats; D011919:Rats, Inbred Strains; D013384:Succinate Cytochrome c Oxidoreductase / Q000037:antagonists & inhibitors
D003524:Cyclosporins; D011522:Protons; D013384:Succinate Cytochrome c Oxidoreductase; D003576:Electron Transport Complex IV