Uptake and retention of selenite and selenomethionine in cultured K-562 cells

The selenium uptake and retention have been studied in K-562 cells exposed to selenite or selenomethionine. In the uptake experiments the cells were exposed to two doses of selenite (5 or 50 microM) or selenomethionine (10 or 50 microM). In the retention study the cells were treated for 2 h with the above mentioned doses of the selenocompounds before being observed at different times. The selenium uptake in cells exposed to selenite 5 microM began to saturate at 8 h, but increased again between 48 and 96 h. In cells exposed to selenite 50 microM the selenium uptake never reached a maximum, however, at 48 and 96 h the cell viability decreased strongly. The two doses of selenite showed different retention patterns, with a relatively small cellular decrease of selenium after treatment with selenite 5 microM compared to treatment with 50 microM of selenite. The selenium uptake in cells exposed to selenomethionine 10 microM or selenomethionine 50 microM began to saturate at 24 h and 48 h, respectively. The retention patterns were similar for both selenomethionine doses with a continuous decrease of the selenium concentration during the whole observation period. The results indicated a more controlled uptake and retention pattern of selenomethionine compared to selenite.