0.1 mL of plasma samples were treated with 30% zinc sulphate for deproteinization followed by centrifugation at 6, 000 rpm for 5 min. 1.0 mL of the supernatant were swirled for 90 min separately with activated cadmium granules for the conversion of nitrite to nitrate and then griess reagent was added. Nitrite concentrations were estimated using a standard curve developed with sodium nitrite. The nitric oxide was evaluated by the sum of values of nitrites and nitrates.