Ca2+-release pathways from mitochondria of the yeast Endomyces magnusii.
Ca2+-release pathways from Ca2+-preloaded mitochondria of the yeast Endomyces magnusii were studied. In the presence of phosphate as a permeant anion, Ca2+ was released from respiring mitochondria only after massive cation loading at the onset of anaerobiosis. Intensive aeration of the mitochondrial suspension rapidly inhibited the efflux of Ca2+ and induced its reuptake. The Ca2+ release was not affected by cyclosporin A, an inhibitor of the nonselective permeability transition of mammalian mitochondria. With acetate as the permeant anion, a spontaneous net Ca2+ efflux began after uptake of about 75% of the added cation. The rate of this efflux was insensitive to cyclosporin A, aeration, and Na+ and was proportional to the Ca2+ load. The Ca2+ release was inhibited by La3+, Mn2+, Mg2+, TPP+, and nigericin (in the presence of KCl) and activated by spermine and hypotonicity. We conclude that Ca2+ efflux from preloaded E. magnusii mitochondria is very similar to the Na+-independent specific pathway for Ca2+ release operative in mitochondria from nonexcitable mammalian tissues.
Deryabina
Y I
YI
Bach Institute of Biochemistry, Russian Academy of Sciences, Moscow, 117071, Russia.
Bazhenova
E N
EN
Zvyagilskaya
R A
RA
D002118:Calcium / Q000378:metabolism*; D017136:Ion Transport / Q000187:drug effects; D008670:Metals / Q000494:pharmacology; D008928:Mitochondria / Q000378:metabolism; D009861:Onium Compounds / Q000494:pharmacology; D009943:Organophosphorus Compounds / Q000494:pharmacology; D004718:Saccharomycetales / Q000187:drug effects / Q000378:metabolism*; D012964:Sodium / Q000378:metabolism; D013096:Spermine / Q000494:pharmacology
D008670:Metals; D009861:Onium Compounds; D009943:Organophosphorus Compounds; D013096:Spermine; D012964:Sodium; D002118:Calcium; C013289:tetraphenylphosphonium