Effect of Mg2+ on membrane fluidity and K+ transport in rat liver mitochondria

Erzsébet Ligeti, LászlóI Horváth

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Abstract

1. The effects of Mg2+ on the fluidity and on the transport properties of mitochondrial inner membrane were compared in parallel experiments. The fluidity was measured by intercalated fatty acid spin probes. Valinomycin-induced K+ uptake was followed using an ion-selective electrode. 2. The rotational diffusion rate of lipids was very slightly affected by Mg2+, whereas the ordering of the probed region of the inner membrane increased considerably above 30°C in the presence of Mg2+ . Mg2+ strongly inhibited K+ transport, particularly above 30°C. 3. In the presence of different concentration of MgCl2 (0–30 mM) the order parameter showed no significant variation, whereas the rotational correlation time had essentially biphasic character with a minimum (i.e., faster diffusion rate) at 10 mM MgCl2. 4. We conclude that Mg2+ induces structural changes in the mitochondrial inner membrane and concomitant changes in its functional properties. The term ‘fluidity’ is inadequate for the interpretation of the data, since changes in the order parameter and in the characteristic correlation time of the inner membrane upon addition of Mg2+ did not show parallel tendencies.

Original languageEnglish
Pages (from-to)150-156
Number of pages7
JournalBiochimica et Biophysica Acta - Biomembranes
Volume600
Issue number1
DOIs
Publication statusPublished - Jan 1 1980

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Keywords

  • Fatty acid
  • Fluidity
  • K transport
  • Mg
  • Rat liver mitochondria

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Cell Biology

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