Effect of cadmium on the extracellular Na+, K+, and Ca2+ in the gill and small intestine of Goldfish Carassius auratus

•The toxic effect of Cd2+ on extracellular Na+, K+, and Ca2+ was determined.•The cations were determined with the technique of ion chromatograph.•Ca2+ was inhibited by Cd2+ in the gill of the goldfish.•The method was rapid, precise and accurate to study cation level in the tissues.

In this study, the toxic effect of cadmium on extracellular Na+, K+, and Ca2+ in the gill and small intestine of goldfish Carassius auratus was determined with the technique of ion chromatograph. Two-way ANOVA indicated that the two factors (Cd2+ treatment and time) and the interaction factor had significant effect on the level of Na+, K+, and Ca2+ in the small intestine and gill. 1.0 mg/L Cd2+ significantly increased Ca2+ level in the small intestine, but Ca2+ level in the gill was significantly decreased by 1.0 and 5.0 mg/L Cd2+ at 24, 48, and 72 h. Na+ and K+ level in the small intestine and gill was increased by 1.0 mg/L Cd2+ at three time points, but increased by 5.0 mg/L Cd2+ at a certain different time. In addition, Na+ level was significantly decreased by 5.0 mg/L Cd2+ at 24 or 48 h in the small intestine and gill. The results indicated that Cd2+ played an important role in regulating the level of Na+, K+, and Ca2+ in the small intestine and gill of goldfish C. auratus. A method was constructed to investigate the extracellular Na+, K+ and Ca2+ in the tissues of gold fish with ion chromatography.