Calcium‐induced Cytochrome c release from CNS mitochondria is associated with the permeability transition and rupture of the outer membrane

• Published in: Journal of neurochemistry 2002-01, Vol.80 (2), p.207-218
• Main Authors: Brustovetsky, Nickolay, Brustovetsky, Tatiana, Jemmerson, Ronald, Dubinsky, Janet M.
• Format: Article
• Language: English
• Subjects: Animals; apoptosis; Apoptosis - physiology; Astrocytes - cytology; Biochemistry and metabolism; Biological and medical sciences; Calcium - pharmacology; Cell Membrane Permeability - drug effects; Cell Membrane Permeability - physiology; Cell Respiration - drug effects; Cell Respiration - physiology; Cells, Cultured; Central nervous system; Cerebral Cortex - cytology; Cytochrome c Group - metabolism; excitotoxicity; Fundamental and applied biological sciences. Psychology; glutamate; Glutamic Acid - toxicity; Mitochondria - metabolism; Mitochondrial Swelling - physiology; neurons; Neurons - cytology; Neurons - metabolism; Neurotoxins - toxicity; Rats; respiration; Vertebrates: nervous system and sense organs
• ISSN: 0022-3042; 1471-4159
• DOI: 10.1046/j.0022-3042.2001.00671.x

The mechanisms of Ca2+‐induced release of Cytochrome c (Cyt c) from rat brain mitochondria were examined quantitatively using a capture ELISA. In 75 or 125 mm KCl‐based media 1.4 µmol Ca2+/mg protein caused depolarization and mitochondrial swelling. However, this resulted in partial Cyt c release only in 75 mm KCl. The release was inhibited by Ru360, an inhibitor of the Ca2+ uniporter, and by cyclosporin A plus ADP, a combination of mitochondrial permeability transition inhibitors. Transmission electron microscopy (TEM) revealed that Ca2+‐induced swelling caused rupture of the outer membrane only in 75 mm KCl. Koenig's polyanion, an inhibitor of mitochondrial porin (VDAC), enhanced swelling and amplified Cyt c release. Dextran T70 that is known to enhance mitochondrial contact site formation did not prevent Cyt c release. Exposure of cultured cortical neurons to 500 µm glutamate for 5 min caused Cyt c release into the cytosol 30 min after glutamate removal. MK‐801 or CsA inhibited this release. Thus, the release of Cyt c from CNS mitochondria induced by Ca2+in vitro as well as in situ involved the mPT and appeared to require the rupture of the outer membrane.