title: Ca2+ transport in mitochondria of the ciliate protozoan Tetrahymena pyriformis.
abstract: Mitochondria isolated from the late-exponential non-shaken culture of the ciliate protozoan Tetrahymena pyriformis GL was investigated. The presence of energy-dependent Ca2+ transport system was shown. In the main the properties of this system have been essentially the same as in mitochondria of vertebrate organisms. The isolated mitochondria contained 23 +/- 5 ng-ion Ca2+ per mg of protein. The intramitochondrial free concentration of Ca2+ was measured in the presence of uncoupler FCCP with the use of fluorescent Ca2+ chelator chlortetracycline and null point titration method. In the absence of phosphate, free [Ca2+] varied from 1 to 2.5 mM depending on the internal Ca2+ content. In the presence of 2 mM phosphate, free [Ca2+]in has not exceeded 0.1-0.3 mM. It was shown that ruthenium red and Mg2+ in different manner have an inhibitory effect on Ca2+ transport. Besides this, Mg2+ also has a stabilizing effect on mitochondria, possibly, by preventing passive ions leaks across the membrane.
mesh_terms: D000244:Adenosine Diphosphate / Q000378:metabolism; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002751:Chlortetracycline; D004734:Energy Metabolism; D006863:Hydrogen-Ion Concentration; D008274:Magnesium / Q000502:physiology; D008928:Mitochondria / Q000378:metabolism*; D009243:NAD / Q000378:metabolism; D010101:Oxygen Consumption; D012430:Ruthenium Red; D013769:Tetrahymena pyriformis / Q000378:metabolism*
chemical_list: D009243:NAD; D012430:Ruthenium Red; D000244:Adenosine Diphosphate; D008274:Magnesium; D002118:Calcium; D002751:Chlortetracycline