Effects of Kappa-selenoearragreenan, an organic compound containing selenium, on heart glutathione peroxidase (GSH-px) were studied in rats. Eight groups of Wistar rats were fed So-deficient or Se-supplemented diets for 54d. After 52d, 4 groups of them were treated with ig 100mg·kg-1 NaNO2 tiwce daily for 3d. Results revealed in comparison with Se-deficient group the heart GSH-px activity were very significantly elevated from 48.6±17.5 to 127.0 ± 34.9, 136.0 ±25.2 and 138.0 ± 52.9u/mg protein respectively i...