The Alteration and Significance of Surfactant Protein A in Rats Chronically Exposed to Cigarette Smoke

In order to confirm the alteration and significance of cigarette smoke exposure on SP-A in rats, 20 Wistar rats were assigned randomly to two groups： an N group （n=10）, and an S group （n=10）. The ultra-structural change was observed by electron microscopy. The number of cells positive for SPA was by immunohistochemically measured. The mRNA expression in the lung tissues was determined by reverse transcription polymerase chain reaction （RT-PCR）. The number of cells positive for SPA of the S group （0.52±0.05） was lower than that of the N group （0.72±0.06） （P〈0.05）. The levels of mRNA of SPA in the lung tissues of the S group （0.3522±0.0512） was significantly lower than that of the N group （0.4432± 0.05628） （P〈0.05）. It is concluded that cigarette smoke alone decreased the level of SP-A and that might have an important effect on surfactant metabolism and the host defense functions of surfactant in the peripheral airways, which might play a crucial role in the development of chronic obstructive lung disease.