[Effects of cultural conditions on hexavalent chromium uptake and the cytotoxicity thereof in KB cell culture].

To reveal the effects of cultural conditions on the cytotoxicity of hexavalent chromium, the uptake of sodium chromate (Na2CrO4) by KB cells and the colony-forming efficiency of the cells were examined under various cultural conditions. The results were summarized as follows: 1) The chromium uptake by the cells after a certain period of incubation with hexavalent chromium was inhibited with the decrease of the temperature (3 degrees, 20 degrees, 37 degrees C), increase of the serum concentration (0, 10, 20, 30%) and increase of pH (6.8-8.2) of the medium. In particular, low temperatures inhibited the chromium uptake by the cells remarkably. However, in relation to the serum addition, no marked effect was found. 2) The chromium uptake by the cells increased with the volume of the medium containing an identical concentration of chromium (2 ppm) and then reached saturation when it was about 0.23 microgram per 10(6) cells. On the other hand, the chromium uptake positively correlated with the concentration of chromium and the total chromium in the medium. 3) The difference of chromium uptake by the cells in different culture media was more marked at acidic pH than that at alkaline pH. However, there was no effect of calcium chloride and glucose concentrations on the uptake of chromium. The chromium uptake by the cells in Ca-Mg-free phosphate-buffered solution (PBS(-] was higher than that in other culture media. Consequently, the above results suggested that the chromium uptake by the KB cells might be affected by the various cultural conditions, especially by temperature, pH and medium volume.