Unit V AAssessment#3 Oxidative Stress - Essay Example

Oxidative stress is defined as the injury caused to cells as a result of increased formation of reactive oxygen species (ROS) and or decreased antioxidant reserve. Reactive oxygen metabolites such as OH- , H2O2 and O2- are continuously produced in vivo as products of aerobic metabolism. If the free radicals are not neutralized by endogenous antioxidants, they may endanger cellular integrity by causing oxidative DNA damage, lipid peroxidation and enzymatic oxidation (Gurjar, Molina, & Ojha, 2010: p 190) .

Exposure to particulate matter (PM ) that contains toxic substances on their surface induces the production f ROS and hence the oxidative stress.In order to eavaluate thr ability of particulate air pollution to promote oxidative stress, six adult pathogen free Sprague-Dawley rats were obtained from Taconic Farms in New York,USA, and fed with conventional laboratory diet and water ad libium.Three of the rats were exposed to filtered air (control group) and the other three were exposed to concentrated ambient particles (CAPs).

Throughout the study, all rats were awake and unrestricted. At 1, 3 and 5 hours, two rats: 1 from filtered air and 1 from CAPs , were removed and analysed. The rats that were exposed to CAPs aerosols for 5 hours showed significant oxidative stress. The rats showed significant increase in lung and heart water content (about 5% , p < 0.05), and increased serum levels of lactase dehydrogenase ( about 80 %) , an indication that there was mild damage to both tissues. Also, there were tissue –specific increases in activities of anti-oxidant enzymes superoxide dismutase (SOD) and catalase.

Generally, exposure to CAPs increased the steady concentration of oxidants in the heart and lung of the rats (Gurgueira, Lawrence, Coull, Murthy, & González-Flecha, 2002: p. 749 and 750). According to Gurgueira, et al., (2002 p.260), the generation of ROS can induce cellular oxidative stress and biological effects,including DNA damage.In most aerobic cells, electron –transport chains are located in mitochondria and the endoplasmic reticulum . The electron –transport chains are the major source of ROS produced in vivo (Gurjar, et al., 2010: p.190).

REFERENCESGurgueira, S. A., Lawrence, J., Coull, B., Murthy, K. G. G., & González-Flecha, B. ( 2002). Rapid increases in the steady-state concentration of reactive oxygen species in the lungs and heart after particulate air pollution inhalation. Environmental Health Perspectives, 110(8), 749-755. Gurjar, B. R., Molina, L. T., & Ojha, C. S. R. (Eds.). (2010). AIR POLLUTION: Health and Evironmental Impacts. New York: CRC Press Taylor & Fancis Group.