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A gated pathway for electrophoretic Na+ fluxes in rat liver mitochondria.
- Source :
-
European Journal of Biochemistry . 2/22/90, Vol. 188 Issue 1, p91-97. 7p. - Publication Year :
- 1990
-
Abstract
- Addition of EDTA to mitochondria incubated aerobically in a phosphate-supplemented medium containing Na+ ions results in activation of cation uptake which is accompanied by membrane depolarization and stimulation of respiration. The same results are obtained in media containing Li+ but not K+, indicating that this pathway for cation transport is selective. The activation of Na+ transport is not accompanied by changes of matrix Mg+. indicating that cation transport is controlled by surface-bound rather than intramitochondrial Mg2+. Na+ transport in respiring mitochondria is competitively inhibited by Mg2+ with a K1 in the nanomolar range. A Na+ current can also be induced by a K+ diffusion potential in the absence of respiration. The K+-diffusion-driven Na+ current has the same magnitude in the absence or presence of inorganic phosphate, suggesting that Na+ transport is mediated by Na+ uniport rather than by electrogenic nNa+/H+ antiport with n > 1. Analysis of the flow/force relationship indicates that the putative Na+ uniporter has a conductance of about 0.2 nmol Na+ × mg protein-1 × min-1 × mV-1, and that it is active only when the membrane potential exceeds about 150 mV. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 00142956
- Volume :
- 188
- Issue :
- 1
- Database :
- Academic Search Index
- Journal :
- European Journal of Biochemistry
- Publication Type :
- Academic Journal
- Accession number :
- 13719425
- Full Text :
- https://doi.org/10.1111/j.1432-1033.1990.tb15375.x