Fig. 3. Rates of proton extrusion by goldfish hepatocytes in response to acidification with 30 mmol l^–1 sodium propionate (see Fig. 2) in standard saline (Cont), with 1 mmol l^–1 amiloride (Am), in low Na⁺ medium (low Na), with 0.5 mmol l^–1 of the anion exchanger blocker SITS (SITS), in Cl^–-free medium (Cl^–-free), with both amiloride and SITS (Am+SITS), and with 0.5 mmol l^–1 iodoacetic acid (IAA). Rates shown were determined from the change of pHi over the first 5 min after the lowest measured pHi was observed. Values are means + S.E.M. of the number of hepatocyte preparations, given in parentheses. * indicates a significant difference from controls and IAA-treated cells (P<0.05, one-way ANOVA followed by Tukey’s procedure).