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Long‐chain fatty acid‐promoted swelling of mitochondria: further evidence for the protonophoric effect of fatty acids in the inner mitochondrial membrane
Author(s) -
Schönfeld Peter,
Więckowski Mariusz R.,
Wojtczak Lech
Publication year - 2000
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(00)01376-4
Subject(s) - valinomycin , protonophore , chemistry , fatty acid , mitochondrion , biochemistry , inner mitochondrial membrane , oxidative phosphorylation , membrane potential , swelling , biophysics , nigericin , membrane , biology , chemical engineering , engineering
Swelling of non‐respiring rat liver mitochondria suspended in isotonic potassium acetate at pH 6.5–7.4 in the presence of valinomycin was promoted by long‐chain fatty acids, such as myristate, indicating a protonophoric mechanism. This swelling was partly inhibited by inhibitors or substrates of mitochondrial anion carriers. The results show that the fatty acid cycling mechanism responsible for uncoupling of oxidative phosphorylation can also operate in the direction opposite to that originally proposed [Skulachev, V.P. (1991) FEBS Lett. 294, 158–162], i.e. the inwardly directed transfer of the fatty acid anion accompanied by outwardly directed free passage of undissociated fatty acid. They also extend the list of mitochondrial anion carriers, that are involved in this process, over the mono‐ and tricarboxylate transporters. At pH 8, myristate, but not the synthetic protonophore, p ‐trifluoromethoxycarbonyl‐cyanide phenylhydrazone, induced mitochondrial swelling in both potassium acetate and KCl media, that did not require the presence of valinomycin. This indicates that, at alkaline pH, myristate facilitates permeation of the inner mitochondrial membrane to monovalent cations and, possibly, activates the inner membrane anion channel.