Objective: To discuss the lung tissue infected by mycoplasma repair mechanism by investigating the influence of Platycodon grandiflorum total saponins on pulmonary surfactant protein A(SP-A) express in lung tissue of rats infected by mycoplasma. Method: Sixty Wistar rat with half males and half females were divided randomly into 6 groups

blank group

model group

positive(azithromycin) group (45 mg·kg-1(first day)

22.5 mg·kg-1(the next day to the fifth day)

the high(56 mg·kg-1)

middle (28 mg·kg-1) and low (14 mg·kg-1)dose group of P. grandiflorum total saponins.the model was established with the method of nasal intubation drop of Mycoplasmal pneumonia(MP). The second day after modeling

azithromycin is given for 5 d

P. grandiflorum t otal saponins is given for 10 d.the lung tissue was collected after 10 days to observe the inflammation of lung tissue by HE staining and to detection of the SP-A mRNA expression level in lung tissue. Using SPSS 17.0 software to analysis data. Result: The pathological results showed that compared with blank group

the interstitial pneumonia of model group was obvious (P <0.01). Compared with model group

the inflammation of lung tissue of positive medicine group

the high

middle and low dose group of P. grandiflorumtotal saponins significantly decreased (P <0.05). The SP-A mRNA expression level in lung tissue showed that compared with blank group

the SP-A mRNA expression of model group significantly lowered (P <0.01). Compared with model group

the SP-A mRNA expression of positive medicine group

the high and middle dose group of P. grandiflorum total saponins obviously up-regulated(P <0.05)

the SP-A mRNA expression of the low dose group of P. grandiflorum total saponins had no significant difference. Conclusion: P. grandiflorum total saponins can improve the lung tissue infected by mycoplasma

and the improving effect of lung function could be realized by raising SP-A expression.