摘要：Effects of sodium ions (Na+) and metabolic inhibitors on cadmium (Cd) uptake were investigated in LLC-PK1 cells derived from pig kidney under the nontoxic conditions of Cd. The inoculated cells became confluent on day 7 after the logarithmic growth phase. The initial uptake of Cd (1-60 μM) by the confluent cells (day 7) was assayed. The relationship between the Cd uptake at 37°C and Cd concentration was nonlinear, but the relationship at 4°C was linear. Subtraction of the Cd uptake at 4°C from that at 37°C showed a saturable uptake against the Cd concentration. By the Eadie-Hofstee analysis of saturable uptake, Km and Vmax were 24.6 μM and 164 pmol Cd/mg protein/min, respectively. The uptake of Cd by the cells was significantly decreased by ouabain and the metabolic inhibitors, and by the replacement of Na+ with potassium or choline ion in the incubation medium. These results suggest that Cd is incorporated into the confluent LLC-PK1 cells not only by simple diffusion but also by the carriermediated transport involved in Na+-and energy-dependent process (es).
