Use of an electrode selective for 1-methyl-4-phenylpyridinium (MPP+) to measure its uptake and accumulation by mitochondria.
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.
Davey
G P
GP
Department of Biochemistry, Trinity College, Dublin, Ireland.
Tipton
K F
KF
Murphy
M P
MP
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
D015655:1-Methyl-4-phenylpyridinium