Calcium-induced Cytochrome c release from rat brain mitochondria is altered by digitonin.
To determine if calcium could release Cytochrome c (Cyt c) from brain mitochondria without activating the permeability transition (mPT), brain mitochondria were prepared in two different ways. Digitonin was used to lyse synaptosomes and release synaptosomal mitochondria or a Percoll gradient was used to separate non-synaptosomal mitochondria from the synaptosomes. In gradient-purified mitochondria, low levels of added digitonin produced swelling and Cyt c release. Digitonin augmented Ca(2+)-induced Cyt c release that was insensitive to the mPT inhibitors, cyclosporin A CsA and ADP. Similarly, in mitochondria prepared with digitonin, these inhibitors also failed to prevent Ca(2+)-induced Cyt c release. Thus the mPT-independent, Ca(2+)-induced Cyt c release pathway was attributable to alteration of the permeability properties of the outer mitochondrial membrane by digitonin.
Brustovetsky
Nickolay
N
Department of Neuroscience, University of Minnesota, 6-145 Jackson Hall, 321 Church Street SE, Minneapolis, MN 55455, USA.
Jemmerson
Ronald
R
Dubinsky
Janet M
JM
D000818:Animals; D001923:Brain Chemistry / Q000187:drug effects*; D002118:Calcium / Q000494:pharmacology*; D003470:Culture Media; D003574:Cytochrome c Group / Q000378:metabolism*; D004072:Digitonin / Q000494:pharmacology*; D066298:In Vitro Techniques; D008353:Mannitol / Q000494:pharmacology; D008564:Membrane Potentials / Q000187:drug effects; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism*; D008933:Mitochondrial Swelling / Q000187:drug effects; D051381:Rats; D013395:Sucrose / Q000494:pharmacology
D003470:Culture Media; D003574:Cytochrome c Group; D008353:Mannitol; D013395:Sucrose; D004072:Digitonin; D002118:Calcium