Fig. 10. The effect of DIDS, an inhibitor of anion 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. DIDS (1 mmoll^-1 in pseudobranch cells and 500 µmoll^-1 in gill cells) was added for the period indicated. Values are means ± S.E.M., N=9 (A); N=11 (B). Asterisks indicate significant differences from values before application of DIDS.