Plasma free amino acids in workers working under different stress conditions

Many harmful occupational factors induce the stress response and result in both the induction of heat stress proteins and the inhibition of the synthesis of other cellular proteins. Since amino acid levels are intimately linked to protein synthesis, we examined the free amino acid levels in the plasma of workers subjected to prolonged exposure to heat, carbon monoxide (CO) or both. The results showed that the revels of most amino acids tended to increase in the plasma of workers in stressful environments, and that free methionine and tryptophan increased significantly (p<0.05) in the heat, CO, and heat+CO groups when compared to a control group. The largest increase was seen in the heat+CO group, followed by the heat group, and finally the CO group. The changes in plasma free amino acid levels in the stress-exposed workers correlate to the induction of heat stress proteins. These findings suggest that the regulation of plasma amino acids levels, by preventing amino acid accumulation possibly resulting from a decrease in the rate of protein synthesis following exposure to stressors, may help to protect workers from these extreme conditions.