FIG. 4.
A: Effect of transmembrane cation gradient on the 3OMG Ci-to-Co dependence on external 3OMG. The dependence of 3OMG Ci-to-Co on 3OMG was compared in extracellular medium containing 137 mmol/l KCl vs. the standard PBS containing 139 mmol/l NaCl. The use of KCl buffer failed to overcome the gradient. The data are representative of one experiment from each of three subjects. B: ATP effects. Preparations of pink ghosts (PG) sealed with the addition of the enzyme apyrase to deplete intracellular ATP failed to shift Ci-to-Co toward unity. However, the preparation of ghosts reduced the 3OMG dependence of the Ci-to-Co ratio and was further reduced by apyrase. The data are representative of one experiment in each of four subjects.