OBJECTIVETo investigate the effect of baicalin (Bai) on lung injury, the level of TNF-alpha in cultured liquid of pulmonary interstitial macrophage and the expression of heme oxygenase-1 (HO-1) in lung injury associated with paraquat poisoning.

METHODSRats were randomizedly divided into four groups: control group, PQ group, Bai group (Bai, 300 mg.kg(-1).d(-1)) and simple Bai group (Bai, 300 mg. kg(-1).d(-1)) (n = 10 in each group). The 2% PQ was injected (25 mg/kg) in PQ group. Bai was injected in the rats (300 mg.kg(-1).d(-1) x 3 d) through caudal vein after paraquat poisoning in Bai group. In simple Bai group, Bai was injected in the healthy rats (300 mg.kg(-1).d(-1) x 3 d). The samples were obtained three days after intraperitoneal administration of 2% paraquat (25 mg/kg). The injury of lung was estimated with HE dyeing and electron microscope. Pulmonary interstitial macrophage (PIM) were obtained, and then cultured for 24 hours. The content of TNF-alpha was evaluated. The expression of HO-1 mRNA was detected by reverse transcription polymerase chain reaction (RT-PCR). The expression of HO-1 protein was evaluated by Western blot analysis.

RESULTSThe lung tissue was normal in control group and simple Bai group. The degree of lung injury in PQ group was higher than that in control group by HE dyeing and electron microscope observation. The level of TNF-alpha expression in cultured PIM in Bai group [(484.2 +/- 39.5) microg/L] was lower than that in PQ group [(790.2 +/- 35.0) microg/L], but higher than that in the control group [(121.6 +/- 19.2) microg/L] (P < 0.05). The expression of HO-1 mRNA and protein [(59.8 +/- 5.40) and (122.0 +/- 31.98)] in Bai group were higher than those in PQ group [(45.9 +/- 5.82) and (77.92 +/- 10.23)] (P < 0.05).

CONCLUSIONThe lung injury associated with paraquat poisoning was alleviated by baicalin, which was possibly related to the decrease of level of TNF-alpha in cultured PIM and the increase of the expression of HO-1 mRNA and protein.