Oligomycin Inhibition of Phosphate Uptake and ATP Labeling in Excised Maize Roots

ATP labeling by newly absorbed (32)P in excised maize roots was reduced 34% by the presence of oligomycin during a 4-min uptake period with no reduction in rate of phosphorus absorption. Longer exposure to oligomycin, during pretreatment periods or longer uptake periods, reduced phosphorus absorption and further reduced ATP synthesis. In these tissues it appears that oligomycin inhibits ATP production at the mitochondria, that ATP is the energy source for phosphorus uptake at the plasmalemma, and that a depletion in the ATP supply causes a reduced rate of uptake.