Active Absorption of Cl– and Na+ in Posterior Gills of Chinese Crab Eriocheir Sinensis: Modulation by Dopamine and cAMP

Abstract

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 |${}^{36}{\rm Cl}^-$| influx. When amiloride, a specific sodium selective channels blocker, was added to the incubation saline, it induced a dramatic decrease of |${}^{22}{\rm Na}^+$| 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 |${}^{22}{\rm Na}^+$| uptake across the epithelium to the hemolymph, suggesting that dopamine stimulates |${\rm Na}^+$| and |${\rm Cl}^-$| influxes via cAMP and |${\rm Na}^+/{\rm K}^+$|-ATPase pathways.