Ruthenium red inhibits mitochondrial Na+ and K+ uniports induced by magnesium removal

András Kapus, Katalin Szászi, Krisztina Káldi, Erzsébet Ligeti, Attila Fonyó

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Abstract

Removal of bound magnesium from the outer surface of the inner mitochondrial membrane opens up a Na+ and Li+ selective electrophoretic uniport pathway whereas simultaneous depletion of intramitochondrial magnesium induces an electrogenic K+ flux as well. In order to clarify the nature of these cation movements we tested the effect of ruthenium red, a potent and specific inhibitor of the mitochondrial Ca2+ uniporter on different Na+ and K+ uniport-associated phenomena. Ruthenium red efficiently inhibited mitochondrial swelling and depolarization induced by either EDTA in a NaCl-based medium (Na+ uniport) or by EDTA plus A23187 in a KCl-based medium (K+ uniport). For both cation uniports half-maximal inhibition was attained at a ruthenium red concentration as low as 40 n.M. Complete inhibition was found above 200 nM. Neither the Na+/H+ nor the K+/H+ exchange was affected by ruthenium red. In light of these observations the possibility is raised that the electrogenic Na+ and K+ fluxes provoked by magnesium reduction or depletion may be mediated through the Ca2+ uniporter. It is suggested that intactness of the mitochondrial magnesium pools is necessary for maintaining the Ca2+ selectivity of the Ca2+ uniporter, and alterations of the membrane-associated magnesium content would make this transport route available also for monovalent cations.

Original languageEnglish
Pages (from-to)18063-18066
Number of pages4
JournalJournal of Biological Chemistry
Volume265
Issue number30
Publication statusPublished - Oct 25 1990

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Ruthenium Red
Ion Transport
Magnesium
Edetic Acid
Cations
Mitochondrial Swelling
Fluxes
Membranes
Monovalent Cations
Depolarization
Calcimycin
Mitochondrial Membranes
Swelling

ASJC Scopus subject areas

  • Biochemistry

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Ruthenium red inhibits mitochondrial Na+ and K+ uniports induced by magnesium removal. / Kapus, András; Szászi, Katalin; Káldi, Krisztina; Ligeti, Erzsébet; Fonyó, Attila.

In: Journal of Biological Chemistry, Vol. 265, No. 30, 25.10.1990, p. 18063-18066.

Research output: Contribution to journalArticle

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