Abstract: Abstract Objective Recent studies have suggested that Na2SiO3 treatment suppresses the development of atherosclerosis in hyperlipemia animal models, to obtain further insight into the mechanism of antiatherothrombotic action of Na2SiO3, we studied the effect of Na2SiO3 on the production of reactive oxygen species（ ROS）by peripheral blood leukocytes(PBL) . Methods 1. PBL separated from health male New Zealand White（NZW）rabbits were exposed to ox-LDL and Na2SiO3 , and then ROS in the cells was quantified by the addition of 2',7'-dichlorofluorescein diacetate (DCFH-DA) . 2. Male NZW rabbits were fed a 0.5% cholesterol diet for 4 weeks. At 4 weeks , the animals were randomized to Na2SiO3 in the drinking water(Na2SiO3 group) or water alone(hyperlipemia group), PBL were separated from the animals to compare the production of ROS . Results Na2SiO3(8.5 mg/L of silicon) treatment dramatically decreased ROS production by ox-LDL stimulated PBL in vitro(fluorescent intensity: 53.3±0.9 vs 61.0±3.1，p﹤0.01）. Although there was no significant difference in blood cholesterol levels between the two groups, ROS levels were significantly lower in PBL of Na2SiO3 group than in hyperlipemia group: fluorescent intensity with stimulation of PMA was 36.55±4.59 and 41.20±3.04（p﹤0.05）respectively，without PMA was 33.15±0.49 and 37.43±0.59（ p﹤0.01）. Conclusions sodium metasilicate inhibited ROS production by ox-LDL-stimulated peripheral leukocytes of rabbit.Administration of Na2SiO3 as drinking water to hypercholesteremia rabbits inhibited the priming and activation of the PBL,and this effect was unrelated to blood cholesterol lowering.

Key words: sodium metasilicate, reactive oxygen species(ROS), leukocytes, atherosclerosis, hypercholesteremia