title: On the state of calcium ions in isolated rat liver mitochondria. III. Diversity of ruthenium red action on different calcium pools.
abstract: Calcium efflux from isolated mitochondria on ruthenium red addition was shown to be biphasic. The rate of efflux from a slowly releasable pool was independent of preincubation. It could be saturated and in extrapolation revealed a maximal rate of 3.6 nmol/(min X mg protein). The efflux from a second, rapidly dischargeable pool was related to calcium added up to 300 nmol/mg protein when a final rate of 15 nmol/(min X mg protein) was reached. The magnitude of the latter pool depended on the time of preincubation in the presence of calcium and correlated with mitochondrial swelling. After ruthenium red addition, a further increase of this pool and spontaneous, destructive calcium release was prevented. Three conclusions are drawn from these results: On preincubation with calcium, part of the mitochondrial calcium develops into a rapidly dischargeable pool. This pool is responsible for mitochondrial alterations resulting in a spontaneous, destructive release of total calcium. Ruthenium red inhibits calcium release by discharging mitochondria from this destructive calcium pool. To avoid artefacts, mitochondrial parameters should be carefully controlled when ruthenium red-insensitive calcium efflux is studied.
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D066298:In Vitro Techniques; D007700:Kinetics; D008930:Mitochondria, Liver / Q000378:metabolism*; D008933:Mitochondrial Swelling / Q000187:drug effects; D010710:Phosphates / Q000494:pharmacology; D051381:Rats; D012428:Ruthenium / Q000494:pharmacology*; D012430:Ruthenium Red / Q000494:pharmacology*
chemical_list: D010710:Phosphates; D012430:Ruthenium Red; D012428:Ruthenium; D002118:Calcium