Abstract: The rate constants of transmembrane transport of Ni²⁺and Cd²⁺ with the same charge and different configurations of electron were determined in this experiment, and their first-order kinetic rate constant is as follows: for Ni²⁺, k(Ni²⁺)=0.002 0 h^-1, and for Cd²⁺, k(Cd²⁺)=0.021 h^-1. There are large differences between their rates of transmemebrane transport. The mechanisms of transmembrane transport of Ni²⁺and Cd²⁺ are studied at the same time. The influences of the concentration of metal ions, pH of solution and the transport inhibitor on the uptake of Ni²⁺and Cd²⁺ by human erythrocytes have been studied. The results show that Ni²⁺ions pass through the membrane by passive diffusion, while for Cd²⁺, some of them are transported by the anion channel, the others by passive diffusion. Because there are different configurations of electron in the two ions, there are large difference in action of them with protein in the membrane of human erythrocytes.

Key words: Metal ions, Human erythrocyte, Transmembrane transport