Enhancement of the uptake of 1-methyl-4-phenylpyridinium ion (MPP+) in mitochondria by tetraphenylboron

The uptake of 1-methyl-4-phenylpyridinium (MPP+) by intact mitochondria was measured by an electrode sensitive to MPP+. The electrode was constructed with a polyvinyl chloride membrane that contained tetraphenylboron (TPB) as an ion-exchange. MPP+ was taken up by mitochondria in an energy-dependent...

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Bibliographic Details
Published in:Biochimica et biophysica acta Vol. 1103; no. 2; p. 233
Main Authors: Aiuchi, T, Syou, M, Matsunaga, M, Kinemuchi, H, Nakaya, K, Nakamura, Y
Format: Journal Article
Language:English
Published: Netherlands 31-01-1992
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Summary:The uptake of 1-methyl-4-phenylpyridinium (MPP+) by intact mitochondria was measured by an electrode sensitive to MPP+. The electrode was constructed with a polyvinyl chloride membrane that contained tetraphenylboron (TPB) as an ion-exchange. MPP+ was taken up by mitochondria in an energy-dependent process. TPB rapidly enhanced MPP+ uptake by mitochondria, and then induced release of MPP+ from mitochondria in medium containing glutamate and malate. No release of MPP+ from mitochondria after addition of TPB could be observed in medium containing succinate, the oxidation of which is not inhibited by MPP+. The release of MPP+ was caused by respiratory inhibition by MPP+ taken up in mitochondria. Since the release of MPP+ did not increased O2 uptake in mitochondria, the major part of MPP+ released from the matrix, where no respiratory enzyme inhibited by MPP+ exists. We concluded the following effect of TPB on MPP+ uptake from the results: (1) The increase of MPP+ concentration in matrix by addition of TPB increased the amount of bound to the inner membranes of mitochondria. (2) The increase of the amount of MPP+ in the inner membranes enhanced the respiratory inhibition. (3) The respiratory inhibition induced to release MPP+ from the matrix. The relation between MPP+ distribution in the membrane of mitochondria and the respiratory inhibition by MPP+ are discussed.
ISSN:0006-3002
DOI:10.1016/0005-2736(92)90092-Z