Isolated posterior gills from the Chinese crab Eriocheir sinensis acclimated to freshwater (FW) were used for perfusion. Dopamine and dibutyryl cAMP (db-cAMP) induced a significant increase of ³⁶Cl^– influx. When amiloride, a specific sodium selective channels blocker, was added to the incubation saline, it induced a dramatic decrease of ²²Na influx, and such an effect could be reversed by dopamine or db-cAMP. In the same experimental condition, we observed that ouabain added to the serosal side induced a marked decrease of the stimulating effect of db-cAMP on ²²Na uptake across the epithelium to the hemolymph, suggesting that dopamine stimulates Na and Cl^– influxes via cAMP and Na /K -ATPase pathways.