Fig. 1. Effect of bafilomycin A₁ exposure on acidification current. Separate experiments are shown in A and B. In both experiments, turtle bladders were mounted in Ussing chambers as described in Materials and methods and exposed to 0.2 mmol l^-1 ouabain in the serosal solution (arrow) to eliminate sodium transport. When the short circuit current (acidification current) subsequently reached a new steady state, the bladder was exposed to either 5 nmol l^-1 bafilomycin A₁ in the serosal bathing solution (A) or to a graded sequence of bafilomycin A₁ concentrations in the mucosal solution (B; final concentrations are shown in nmol l^-1). Baf, bafilomycin A₁. Short circuit current shown is in µA (per area of chamber, 1.43 cm²). The unlabeled number in the lower right of each panel is an index number identifying the experiment.