Fig. 8. The effect of amiloride, an inhibitor of Na⁺/H⁺-exchange, on the rate of acidification of the external medium induced by acid secretion of isolated pseudobranch cells (A) and gill cells (B) as a function of time. Amiloride (50 µmoll^-1) was added for the period indicated. Values are means ± S.E.M., N=12 (A); N=7 (B). Asterisks indicate significant differences from values before application of amiloride.