Fig. 7. Effects of bath K⁺ concentration (10 or 6 mmol l^–1) on fluid secretion rate (mean ± S.E.M.) and ion flux (mean ± S.E.M.). (A) Fluid secretion rates of tubules bathed in saline containing 10 or 6 mmol l^–1 K⁺ are shown before (filled columns) and 10 min after (open columns) addition of 10^–5 mol l^–1 bumetanide. (B) Na⁺ fluxes and K⁺ fluxes of tubules bathed in saline containing 10 or 6 mmol l^–1 K⁺. Different letters in each panel denote columns that differ significantly by (A) two-way ANOVA and Tukey HSD for unequal sample sizes or (B) one-way ANOVA and Tukey–Kramer multiple comparisons. N=5–10 tubules per column.