Vitamin C and E supplements were administered to sodium nitrate-treated rats in order to examine the possible ameliorative effects of these antioxidants on erythrocyte osmotic fragility. Seventy adult Wistar rats were randomly divided into seven groups (n=10) and administered drugs or distilled water orally using a metallic canular for 60 days. Group I (control) received distilled water; Group II - 30 mg/kg NaNO3; Group III – 30 mg/kg NaNO3 + 500 mg/kg vitamin C; Group IV – 30 mg/kg NaNO3 + 750 mg/kg vitamin C; Group V – 30 mg/kg NaNO3 + 300 mg/kg vitamin E; Group VI – 30 mg/kg NaNO3 + 400 mg/kg vitamin E; Group VII - 30 mg/kg NaNO3 + 500 mg/kg vitamin C + 300 mg/kg vitamin E. Blood was collected from each animal at the end of the experiment to determine erythrocyte osmotic fragility. The results showed that, sodium nitrate caused significant decrease in erythrocyte osmotic fragility. Each of the vitamin administered separately increased erythrocyte osmotic fragility back to normal values. However, co-administration of the two vitamins very significantly increased erythrocyte osmotic fragility to above normal values. It was concluded that, vitamin C and E administered separately ameliorated sodium nitrate toxicity in a dose dependant manner. Co-administration of the two vitamins showed synergistic effect which was detrimental to the rats due to the risk of anaemia.
Keywords: antioxidants, vitamin C, vitamin E, sodium nitrate, erythrocytes, osmotic fragility, rats.