The Effects of Noise on Oxidative and Antioxidative Balance in Human Erythrocytes

Abstract

Reactive oxygen and nitrogen species have been implicated in the pathogenesis of noise-induced hearing loss. In this case-control study, we investigated the oxidative and antioxidative status of erythrocytes from workers in noisy workplace. Blood samples of 127 workers in noisy workplace (WNW) and 117 workers in non-noisy workplace (WNNW) from the same company were taken into tubes with potassium EDTA as anticoagulant in order to obtain hemolysate. Total superoxide dismutase (SOD) and catalase (CAT) activities as the enzymes of antioxidative defense mechanism in the erythrocytes together with malondialdehyde (MDA) as the lipid peroxidation index and total nitric oxide (NO) as an index for nitrogen species analyses were performed by spectrophotometric methods. SOD activity was found to be 450.0 +/- 106.4 U/g Hb in WNW and 443.1 +/- 83.1 U/g Hb in WNNW. The difference between two groups were not statistically significant (p= 0.582). CAT activity was found to be 426.0 +/- 98.0 k/g Hb in WNW and 432.6 +/- 109.0 k/g Hb in WNNW showing statistically insignificant difference (p= 0.621). MDA levels in erythrocytes from WNW was significantly higher than WNNW (39.28 +/- 10.22 nmol/g Hb and 32.51 +/- 10.73 nmol/g Hb, respectively and p= 0.0001). On the other hand, NO levels were found to be significantly reduced in WNW (0.275 +/- 0.187 mu mol/g Hb) compared to WNNW (0.382 +/- 0.284 mu mol/g Hb) (p= 0.001). When we analyzed the hematological parameters, all the cell counts increased in WNW except monocytes and platelets compared to WNNW (p= 0.0001). Related to this changes, hemoglobin, MCHC, and hematocrit also increased in WNW (p= 0.0001). The oxidative stress, which is possibly propagated by the physical environment, seems to have an important pathophysiological role in hearing loss and lipid peroxidative cellular changes in all of the workers who work in noisy occupations.