Acclimation to Copper by Rainbow Trout,<i>Salmo gairdneri</i>: Physiology

Abstract

Juvenile rainbow trout (Salmo gairdneri) were exposed to 55 μg copper∙L −1 for 28 d and then transferred to uncontaminated water for 7 d. Whole body sodium concentration and sodium uptake (J in ) were measured at weekly intervals; J in was measured at various Na + concentrations and kinetic parameters estimated. After 24 h of copper exposure, the maximum rate of sodium uptake (J max ) was inhibited by 55%, the affinity for sodium (K m ) reduced by 49%, and whole body Na + decreased by about 12.5%. After 7 d of exposure, whole body Na + had returned to control values, but J max was still inhibited by 41%. Recovery of whole body Na + occurred largely by a reduction of sodium efflux (J out ). Both J max and K m continued to recover until day 28, at which time J in had returned to control values. We conclude that acclimation to sublethal copper depends on changes in both Na + transport and permeability.