title: Use of an electrode selective for 1-methyl-4-phenylpyridinium (MPP+) to measure its uptake and accumulation by mitochondria.
abstract: An ion-selective electrode specific for the 1-methyl-4-phenylpyridinium ion (MPP+) was developed which allowed the measurement of the initial rate of uptake and the extent of accumulation of MPP+ by rat liver mitochondria. Using this electrode we demonstrated that the initial rate of uptake of MPP+ was not saturable and that the distribution of MPP+ across the mitochondrial inner membrane did not equilibrate with the membrane potential, in contrast to other lipophilic cations such as the methyltriphenyl phosphonium ion (TPMP+). Furthermore, incubation of mitochondria respiring on succinate with MPP+ decreases the membrane potential. The possibility that the interaction of MPP+ with mitochondria may be more complex than accumulation followed by inhibition of site 1, suggested by these and other data, is discussed.
authors.affiliation: Department of Biochemistry, Trinity College, Dublin, Ireland.
authors.forename: G P
authors.initials: GP
authors.lastname: Davey
authors.forename: K F
authors.initials: KF
authors.lastname: Tipton
authors.forename: M P
authors.initials: MP
authors.lastname: Murphy
mesh_terms: D015655:1-Methyl-4-phenylpyridinium / Q000378:metabolism*; D000818:Animals; D001692:Biological Transport; D004563:Electrochemistry / Q000295:instrumentation / Q000379:methods; D007425:Intracellular Membranes / Q000378:metabolism; D007700:Kinetics; D008297:Male; D008930:Mitochondria, Liver / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar
chemical_list: D015655:1-Methyl-4-phenylpyridinium