Inhibition of acetate- and MCA- uptake by other solutes. Uptakes of 50 μM of [2-14C] labelled acetate or MCA were determined in the presence of competing solutes. The assays were conducted for 1 min. Competing solutes were added to a final concentration of 0.5 mM. Competing solutes used were: ethanol, formate, glycolate, lactate, pyruvate, succinate, acetate, MCA, MBA, propionate, 2MCPA, butyrate, and valerate. Uptake rates without competitor were used as the controls. Data shown are the means of three independent experiments, and the error bars represent the standard deviations. (A) Acetate uptake of acetate-grown cells; (B) Acetate uptake of MCA-grown cells; (C) MCA uptake of MCA-grown cells.