Effects of atrazine on osmoregulation in the Chinese mitten crab, Eriocheir sinensis.

This study integrates results from acute contamination with atrazine of isolated perfused gills, and from in vivo chronic contamination of euryhaline Chinese mitten crabs, Eriocheir sinensis, acclimated to freshwater. Atrazine 1 mg/l in contact with the basolateral membrane (IN) increases the transepithelial potential difference (TEP) from -20.8 +/- 4.9 to -29.7 +/- 3.8 mV in isolated perfused posterior gills (P < 0.01). This effect is only partially explained by a modification of Na(+) and Cl(-) active influxes. No TEP modification is detected when atrazine is added (OUT) indicating that molecular mechanisms located on the basolateral membrane are likely to be the only ones affected. Another explanation would be that cuticular barrier prevents atrazine penetration into the gill. Haemolymph osmolarity, Na(+) and Cl(-) concentrations of crabs living in freshwater contaminated with atrazine 1 mg/l during 14 days are not significantly modified. We conclude that although atrazine can disturb osmoregulatory mechanisms of isolated gills, this pollutant would be of minor importance in affecting osmoregulatory capacities of the Chinese mitten crab in natural conditions.