title: Studies on the ionophorous antibiotics. XVI. The ionophore-mediated calcium transport and concomitant osmotic swelling of mitochondria.
abstract: The effects of various carboxylic ionophores on divalent metal cation translocation in mitochondria have been investigated. High levels of divalent cation ionophores lysocellin and lasalocid A (10 approximately 50 micrometer) produced mitochondrial osmotic swelling in Ca2+ or Mg2+ medium, which was associated with an increase of cation influx. The extent of swelling was a function of both the ionophore and cation concentrations in the medium. This effect was larger in mitochondria de-energized by treatment with antimycin A and oligomycin than in respiring mitochondria. On the other hand, the monovalent cation ionophores carriomycin and etheromycin at concentrations of 50 approximately 100 micrometer also induced mitochondrial swelling in Ca2+ medium but were ineffective in Mg2+ medium. Addition of ruthenium red reversed divalent cation ionophore-induced swelling and released Ca2+ from preloaded mitochondria. In contrast, ruthenium red increased monovalent cation ionophore-induced swelling. In a divalent cation-free medium, lysocellin and lasalocid A caused depletion of membrane-bound Ca2+ and released endogenous Ca2+ and Mg2+ from mitochondria, while carriomycin and etheromycin exerted only a limited effect. These results indicate that the divalent cation ionophores affect divalent cation distribution in mitochondria by increasing both influx and efflux of the cations through the inner membrane.
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001692:Biological Transport / Q000187:drug effects; D002118:Calcium / Q000378:metabolism*; D066298:In Vitro Techniques; D007476:Ionophores / Q000494:pharmacology*; D008274:Magnesium / Q000378:metabolism; D008297:Male; D008928:Mitochondria / Q000378:metabolism*; D008930:Mitochondria, Liver / Q000187:drug effects / Q000378:metabolism; D008933:Mitochondrial Swelling / Q000187:drug effects*; D051381:Rats
chemical_list: D000900:Anti-Bacterial Agents; D007476:Ionophores; D008274:Magnesium; D002118:Calcium