Protonmotive force in muscle mitochondria

David A. Stumpf*, Richard Haas, Luis A. Eguren, Janice K. Parks, Robert E. Eilert

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

11 Scopus citations


The protonmotive force (Δp) of muscle mitochondria was measured by estimating the distribution of 14C‐labeled TPMP (trimethylphenylphosphonium iodide) and 14C‐labeled acetate across the inner membrane of muscle mitochondria. The matrix volume was simultaneously determined using 3H‐labeled H2O and 3H‐labeled mannitol and repeated drying to distinguish the label in these 2 compounds. Rapid separation of mitochondria from the incubation medium by centrifugation through silicone oil avoids the problems of potential anaerobic conditions associated with conventional centrifugation and large volumes of trapped media associated with filtration. The value for Δp (mean ± SD) was 192 ± 26 mV in 30 determinations with rat muscle mitochondria during state 4. Measurement of oxygen consumption allowed calculation of membrane conductance (Cm, H+) which was 0.49 ± 0.18 nmol of H+/min/mg protein/mV. The values for δp and Cm, H+ are reported for a variety of experimental conditions and are consistent with Mitchell's chemiosmotic theory. Biopsy specimens obtained from human muscle gave state‐4 Δp values of 197 ± 30 mV (n = 5) and Cm, H+ values of 0.52 ± 0.12 nmol of H+/min/mg/mV (n = 4). This Δp assay is the first described for coupled mammalian muscle mitochondria and will be useful in assessing membrane function.

Original languageEnglish (US)
Pages (from-to)14-19
Number of pages6
JournalMuscle & Nerve
Issue number1
StatePublished - Jan 1982

ASJC Scopus subject areas

  • Clinical Neurology
  • Physiology (medical)
  • Cellular and Molecular Neuroscience
  • Physiology


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