[Effects of high dose ambroxol on lung injury induced by paraquat in rats].

Objective: To evaluate the protective effect of high dose ambroxol, a mucoactive drug, on acute lung injury caused by paraquat in rats.

Methods: One hundred and thirty-six healthy male Sprague-Dawley rats were randomly divided into three groups: control group (n = 24) injected with normal saline intraperitoneally, PQ group (n = 56) [(2% paraquat (25 mg/kg) injected into peritoneal cavity on the first day)] and AT group (n = 56) ambroxol 35 mg/kg was injected into peritoneum daily after paraquat intoxication once daily for 7 consecutive days. The arterial gas was determined and the extent of lung injury was assessed by measuring the ratio of wet to dry weight (W/D) and protein content in BALF, the WBC count, the percentage of PMN, the content of malondialdehyde (MDA) and the levels of superoxide dismutase (SOD) in the blood and BALF respectively. Left lung tissue was observed through both light microscope and electron microscope (TEM).

Results: The white cell count and the content of protein in the blood and the BALF of PQ group were significantly higher than those of the control group (P < 0.05 or P < 0.01). On the 7th day, the content of MDA 9 [(8.12 +/- 1.12) nmol/ml] in the serum of PQ group was significantly higher than the control group and the GSH-Px activity [(1256.8 +/- 133.2) U/ml] was significantly lower than the control group (P < 0.01). The white cell count and the content of protein in the blood and the BALF of AT group were significantly lower than the PQ group (P < 0.05 or P < 0.01). On the 7th day, the content of MDA in the serum of the AT group [(4.86 +/- 0.75) nmol/ml] was significantly lower than the PQ group and the GSH-Px activity [(1509.5 +/- 183.0) U/ml] and the SOD activity [(3903.2 +/- 374.7) U/ml] were significantly higher than the PQ group (P < 0.01). Under optical and electronic microscopes, the injury of lung tissue was reduced after large dose of ambroxol was administered.

Conclusion: Treatment with ambroxol (35 mg/kg) could influence the status of oxidative stress in lung and alleviate lung injury induced by paraquat. Ambroxol has obviously therapeutic effect on paraquat poisoning.