EFFECTS ON ANTIOXIDANT SYSTEM OF CARDIAC TISSUE FOLLOWING REPEATED ORAL ADMINISTRATION OF ARSENIC, QUINALPHOS AND THEIR COMBINATION IN WISTAR RATS

Prevalence of insecticides and toxic metals in nature is a potential threat to mammalian well being. Simultaneous exposure to co-existing environmental toxins can severely impair cardiovascular health possibly by compromising cardiac antioxidant system. The present study was conceptualized to determine the consequences of concurrent exposure to arsenic and quinalphos on antioxidant status of cardiac tissue in rats. Fifty-four adult Wistar rats of either sex were randomly allocated to nine groups of six rats each. Animals were subjected to either individual or simultaneous oral administration of quinalphos (1/100th or 1/10th of LD50) and arsenic (50 or 100 ppb) incorporated in drinking water, for 28 days. Significantly (p<0.05) declined cardiac antioxidant biomarkers viz. total thiols, catalase, superoxide dismutase, glutathione peroxidase, glutathione-s-transferase, glutathionc reductase along with increased (p<0.05) malondialdehyde levels indicated oxidative damage to heart following simultaneous administration of higher doses of quinalphos and arsenic when compared not only to control rats but also to rats exposed to either toxicant. Likewise, significant reduction in activity of cardiac acetylcholinesterase (AChE) was seen in rats co-exposed to higher doses of quinalphos and arsenic. These results show that simultaneous co-exposure to arsenic and quinalphos particularly at their higher doses imposed severe cardiac oxidative stress in rats as reflected by reduced antioxidant biomarkers, increased lipid peroxidation and reduced AChE activity.