The MannWhitneyUtest was used to compare results of the Zn-exposed groups with those of the control group. MichaelisMenten analysis of the relationship between external Cd concentration and apical uptake influx of Cd at different Zn concentrations were performed by estimation of J the maximum rate of uptake influx max and K the Cd conc. resulting in 1 2 J . mmax Non-linear regressions were performed on all individual values of apical uptake and influx using SigmaPlot 4.0 for Windows 95 SPSS Inc., Chicago,. USA . The parameter estimates obtained in the non-linear regression were compared using at-test for unequal variances . The level of significance was set toP 0.05 in all tests.