Calcium efflux mechanism in sperm mitochondria

Haim Breitbart, Sara Rubinstein, Michal Gruberger

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    14 Scopus citations


    This paper reports an investigation on calcium efflux mechanism in ram sperm mitochondria. Energized sperm mitochondria take up Ca2+ via the ruthenium-red sensitive uniporter, and possess a ruthenium-red insensitive efflux mechanism. Extramitochondrial Na+ did not affect the rate of Ca2+ efflux indicating that Na+/Ca2+ exchange mechanism is not involved. Depolarization of inner mitochondrial membrane induced by the uncoupler carbonylcyanide-p-trifluoromethoxyphenyl hydrazone (FCCP) or by the organomercurial SH-reagent mersalyl, causes high stimulation in Ca2+ efflux. This stimulated Ca2+ efflux determined in the presence of ruthenium-red and phosphate, is not inhibited by cyclosporin A (CSA), indicating that mitochondrial permeability transition pore (MTP) is not involved in this Ca2+ efflux mechanism. The stimulated Ca2+ efflux is inhibited by ADP or atractyloside suggesting that the Ca2+ transport mechanism might be intrinsic to the ADP/ATP carrier (AAC). Thus, the data indicate that sperm mitochondria contain a Ca2+ efflux mechanism operated via AAC and regulated by mitochondrial membrane potential and by ADP concentration.

    Original languageEnglish
    Pages (from-to)79-84
    Number of pages6
    JournalBiochimica et Biophysica Acta - Molecular Cell Research
    Issue number2
    StatePublished - 13 Jun 1996

    Bibliographical note

    Funding Information:
    We thank Avrille Goldreich and Sharon Victor for typing this manuscript. This work was supported in part by a grant from the Ihel Foundation to H.B.


    • Calcium efflux
    • Mitochondrion
    • Spermatozoon


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