Figure 9. Effect of organic and inorganic anions of the extravesicular media on butyrate uptake.

LMV, isolated from pig () and human () colon, were preloaded with the standard loading buffer. LMV (100 μg protein per assay) were then incubated in media containing 100 mm mannitol, 80 mm sodium gluconate (60 mm sodium gluconate when Na₂SO₄ was present in the medium); 20 mm Mes-Tris (pH 5.5), 0.1 mm MgSO₄, 1 mm [U-¹⁴C]butyrate and the following Na⁺ salts (20 mm final concentration) acetate, propionate, pyruvate, l-lactate, Cl⁻, NO₃⁻ and SO₄⁻. Uptake was measured at 37 °C for 5 s as before. Values are presented as means ± s.e.m. for three experiments.