Figure 3: Effects of Alpinia officinarum on the activity of nitric oxide synthase (A) and the content of nitric oxide (B) in serum of particulate matter-induced mice. AO: Alpinia officinarum; PM: particulate matter; LD: low dose; MD: medium dose; HD: high dose. All values are expressed as mean±SD (n=10). ###P<0.001 compared with control group. ***P<0.001 compared with PM group.