CYTOCHROME-C POTENTIATES FATTY ACID-INDUCED CYCLOSPORINE A-SENSITIVE PERMEABILITY TRANSITION IN LIVER-MITOCHONDRIA

Addition of 0.5-5 mu M cytochrome c and 30 mu M lauric acid to rat liv er mitochondria stimulated the respiration rate. Stimulation of respir ation by cytochrome c was prevented by cyclosporin A and was not obser ved in the absence of lauric acid. High amplitude swelling of mitochon dria in the presence of lauric acid was also potentiated by cytochrome c; this effect was prevented by cyclosporin A or by EGTA. Polylysine (0.35 mu M) induced cyclosporin A-insensitive high amplitude swelling of mitochondria. Polylysine-induced swelling was stimulated by lauric acid and cytochrome c; the effect was prevented by cyclosporin A. Incu bation of mitochondria with 30 mu M lauric acid resulted in an increas e in cytochrome c concentration in the incubation medium. Added cytoch rome c is supposed to potentiate the laurate-induced cyclosporin A-sen sitive permeability transition in cytochrome c-depleted mitochondria.