Sodium meta-arsenite induced reactive oxygen species in human red blood cells: impaired antioxidant and membrane redox systems, haemoglobin oxidation, and morphological changes

Arsenic (As) is an air and water toxicant that causes cancer in multiple organs. Humans are exposed to As through contaminated water. We have examined the cytotoxicity of sodium metaarsenite (SA), an As(III) compound, in human red blood cells (RBC) under in vitro conditions. Haemolysates were prepared from human RBC treated with different concentrations of SA (0.1-5.0 mM) for 5 h at 37 degrees C. SA treatment of RBC caused significant increase in methaemoglobin formation, protein and lipid oxidation, and nitric oxide levels. It also resulted in decrease in glutathione levels, methaemoglobin reductase activity and plasma membrane redox system. SA exposure also inhibited the pathways of glucose metabolism while increasing AMP deaminase and glyoxalase-I. It impaired the enzymatic and non-enzymatic antioxidant defence systems which resulted in decreased antioxidant power and a compromised ability to quench free radicals. SA exposure also damaged the membrane since it decreased the activity of membrane bound enzymes, increased the osmotic fragility of treated cells and induced gross morphological changes. This cytotoxicity was the result of oxidative damage since the production of reactive oxygen species (ROS) was increased in SA treated erythrocytes. Thus As(III) causes extensive damage to RBC which impairs their antioxidant system and alters the major cellular metabolic pathways. All this has the potential to lower the oxygen carrying capacity of RBC and reduce their lifespan in blood.