Combined effect of cadmium (CdCl2) and high temperature on HeLa S3 cells.

The combined effect of cadmium (CdCl2) and high temperature on the subsequent growth, the synthesis of nucleic acids and protein, and the cell cycle in HeLa S3 cells was investigated. The subsequent growth rate was depressed by cadmium at 37.1 degrees C. This suppression effect was enhanced at 40.4 degrees C compared with the effect at 37.1 degrees C. The synthesis of DNA, RNA and protein was inhibited at higher temperatures in cultivation without cadmium, and depressed at each temperature in a concentration-dependent manner by the addition of cadmium. The DNA, RNA and protein-IC50 values at 40.4 degrees C decreased compared with the values at 37.1 degrees C. The DNA and RNA-IC50 values were significantly decreased (p less than 0.01, p less than 0.005, respectively) depending on the temperature. After treating the cells with cadmium at 40.4 degrees C, the DNA/BrdUrd distribution showed that the rate of dead cells increased and the rate of the G1/G0 phase decreased. These results indicate that the inhibitory effect of cadmium on the subsequent growth of HeLa S3 cells is enhanced at high temperature and this enhancement is related to the increased inhibitory effect of cadmium on DNA and RNA synthesis at high temperature.