Effects of SF and OMT combination on the lung histopathological changes of PQ-intoxication rats. CON, PQ, SF and OMT represent the control group, paraquat group, sodium ferulate group (3.1 mg/Kg/day) and oxymatrine group (6.9 mg/Kg day), respectively. SF+OMT represents sodium ferulate and oxymatrine combination treatment groups, and the 1.6 + 3.4, 3.1 + 6.9 and 6.2 + 13.8 respectively represent drug administration doses of SF+OMT in the low dose group, middle dose group and high dose group. The degree of lung injury was scored under light microscopy from 0–4 as follow: 0 (no damage), 1 (slight diffuse damage of neutrophilic in alveolar walls, no thickening of alveolar walls, no hemorrhage, < 25 % congestion of alveolar space); 2 (diffuse damage of mononuclear and neutrophilic in alveolar walls and slight thickening of the alveolar walls, at least five erythrocytes per alveolus in one to five alveoli, < 25-30 % congestion of alveolar space,); 3 (two or three times thickening of the alveolar walls, at least five erythrocytes in five to ten alveoli, 30-50% congestion of alveolar space); 4 (alveolar wall thickening with up to 50% of lung consolidated, at least five erythrocytes in more than ten alveoli, > 60 % congestion of alveolar space). Data are expressed as means ± SEM. n = 10 in each group. ##P < 0.01 compared with the control group. *P < 0.05, **P < 0.01 compared with the PQ group.