Calculation of ion currents across the inner membrane of functionally intact mitochondria

Daniel A. Kane, Evgeny Pavlov

Research output: Contribution to journalArticle

Abstract

Mitochondrial ion transport systems play a central role in cell physiology. Rates of Ca2+ and K+ transport across the inner mitochondrial membrane have been derived from the measurement of ion accumulation over time within functional isolated mitochondria or mitochondria of cultured cells. Alternatively, the electrical currents generated by ionic flux have been directly measured in purified and swollen mitochondrial samples (mitoplasts) or reconstituted channels, and typically range from 1 pA to several 100s pA. However, the direct electrophysiological approach necessarily requires extensive processing of the mitochondria prior to measurement, which can only be performed on isolated mitoplasts. To compare rates of mitochondrial ion transport measured in electrophysiological experiments to those measured in intact mitochondria and cells, we converted published rates of mitochondrial ion uptake into units of ionic current. We estimate that for monovalent ions, uptake by intact mitochondria at the rate of 1 nmol · mg-1 protein · min-1 is equivalent to 0.2 fA of current per whole single mitochondrion (0.4 fA for divalent ions). In intact mitochondria, estimated rates of electrogenic cation uptake are limited to 1-100 fA of integral current per single mitochondrion. These estimates are orders of magnitude lower than the currents through mitochondrial channels directly measured via patch-clamp or artificial lipid bilayer approaches.

Original languageEnglish (US)
Article numbera6
JournalChannels
Volume7
Issue number6
DOIs
StatePublished - Nov 2013

Fingerprint

Mitochondria
Ions
Membranes
Ion Transport
Cell Physiological Phenomena
Lipid bilayers
Physiology
Clamping devices
Mitochondrial Membranes
Lipid Bilayers
Cations
Cultured Cells
Cells
Fluxes
Processing

Keywords

  • Calcium
  • Ion transport
  • Lipid bilayer
  • Mitochondria
  • Patch-clamp
  • Potassium

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Medicine(all)

Cite this

Calculation of ion currents across the inner membrane of functionally intact mitochondria. / Kane, Daniel A.; Pavlov, Evgeny.

In: Channels, Vol. 7, No. 6, a6, 11.2013.

Research output: Contribution to journalArticle

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