atractyloside and 6-ketocholestanol

This work shows that 6-ketocholestanol (kCh) inhibits the effect of carbonyl cyanide-m-chlorophenyl hydrazone (CCP) on mitochondrial Ca2+ efflux. Such an effect proved to be caused by diminution of membrane fluidity, therefore, it is affected by the incubation temperature. Furthermore, kCh reversed CCP-induced Ca2+ efflux depending on the accumulation of phosphate. It is also shown that kCh enhances the effect of carboxyatractyloside on membrane permeability transition.

Topics: Animals; Atractyloside; Calcium; Carbonyl Cyanide m-Chlorophenyl Hydrazone; Intracellular Membranes; Ketocholesterols; Kidney; Membrane Fluidity; Mitochondria; Permeability; Rats; Vitamin K

Zearalenone (F-2) is a mycotoxin which acts as a protonophoric uncoupler in plant mitochondria [Macri, F. and Vianello, A., (1990) J. Plant Physiol. 136, 754-757]. In the present paper, the mechanism of F-2-induced uncoupling in pea mitochondria was studied. The uncoupling by F-2 was partially reversed by 6-ketocholestanol (kCh) under conditions in which kCh completely reversed the FCCP-induced uncoupling and almost did not affect the palmitate-induced uncoupling. Recoupling effects of carboxyatractylate, ADP and cyclosporin A were small and could not essentially decrease the kCh-insensitive part of F-2-induced uncoupling. It is suggested that a protein, mediating kCh-sensitive uncoupling, is involved in the F-2 effect in plant mitochondria.

Topics: Atractyloside; Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone; Dose-Response Relationship, Drug; Estrogens, Non-Steroidal; Glutamic Acid; Ketocholesterols; Membrane Potentials; Mitochondria; Palmitic Acid; Plants; Uncoupling Agents; Zearalenone