Effect of mixtures of SO₂ and NO₂ on respiratory system in rats

  Objective   To explore the damage mechanism on respiratory system in rats exposed to mixture of sulfur dioxide(SO₂)and nitrogen dioxide(NO₂).

  Methods   40 rats were randomly divided into 4 groups, i.e.acontrol group and 3 treated groups.Rats in control group were exposed to general air.Mixed gases of SO₂ and NO₂ were inhaled by static state in teated rats, 2 h per day for 21 d.Low, middle and high concentrations of SO₂ and NO₂ were 8 and 5, 16 and 10, 32 and 20 mg/m³ respectively.After 3 weeks, the levels of biochemical indexes and the activities of enzymes in serum and in bronchiolar lavage fluid(BALF)were measured.

  Results   The atcivities of alkaline phosphatase(AKP)and acid phosphatase(ACP)in exposed groups were higher than that in control group(P < 0.01)especially middle and high dosage groups; The levels of malondiadehyde(MDA)and albumin in serum and BALF were increased in treated groups, especially in serum; superoxide dismutase(SOD)in BALF were decreased, there were statistical difference between exposed groups and control group(P < 0.05).

  Conclusion   Mixtures of SO₂ and NO₂ may induce pulmonary epithelial permeability increase and oxidant injury.