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Mitochondrial Ca²⁺ sequestration and precipitation revisited
- Chinopoulos, Christos, Adam-Vizi, Vera
- FEBS journal 2010 v.277 no.18 pp. 3637-3651
- adenine nucleotides, calcium, cations, cell death, mitochondria, oxidative phosphorylation, signal transduction, thermodynamics
- The ability of mitochondria to sequester and retain divalent cations in the form of precipitates consisting of organic and inorganic moieties has been known for decades. Of these cations, Ca²⁺ has emerged as a major player in both signal transduction and cell death mechanisms, and, as a consequence, the importance of mitochondria in these processes was soon recognized. Early studies showed considerable effort in identifying the mechanisms of Ca²⁺ sequestration, precipitation and release by uncouplers of oxidative phosphorylation; however, relatively little information was obtained, and these processes were eventually taken for granted. Here, we re-examine: (a) the thermodynamic aspects of mitochondrial Ca²⁺ uptake and release, (b) the insufficiently explained effect of uncouplers in inducing mitochondrial Ca²⁺ release, (c) the thermodynamic effects of exogenously added adenine nucleotides on mitochondrial Ca²⁺ uptake capacity and precipitate formation, and (d) the elusive nature of the Ca²⁺-phosphate precipitates formed in the mitochondrial matrix.