Fig. 2. Rates of copper (⁶⁴Cu) uptake (pmol g^-1 h^-1) as a function of ambient (A) sodium, (B) potassium and (C) calcium concentration (nmol l^-1) in juvenile rainbow trout assessed during a 2 h incubation in the presence of 200 nmol l^-1 copper. Values are means + S.E.M., N=8 in all cases. An asterisk indicates a statistically significant difference from the corresponding control value (0.05 mmol l^-1); two-tailed Student's unpaired t-test with multisample comparison correction (P<0.05).