Fig. 5. The effect of 1 h of base (3 mmol kg^–1 NaHCO₃) infusion (A) on net excretion of acidic equivalents (J_netH⁺) into the water (branchial) or urine (kidney), as well as total excretion, and (B) on the relative contributions of branchial and renal excretion to total net excretion of acidic equivalents in African lungfish Protopterus annectens. Values are means ± s.e.m. for the period prior to base infusion (`pre'), and for measurement periods immediately following base infusion (0–4 h) and 18 h post-infusion (17–21 h); N=5–7. In A, an asterisk (^*) indicates a significant difference from the pre-infusion value (one-way RM-ANOVA with P values of 0.03, 0.003 and 0.008 for branchial, renal and total J_netH⁺, respectively). Changes in the relative contributions of branchial and renal excretion to total J_netH⁺ were not statistically significant in B.