Abstract: To study the changes of endothelium-derived nitric oxide(EDNO)in pulmonary heart disease, adult male Wistar rats were given a single injection of monocrotaline(MCT)(60 μg/g)to build the model of pulmonary heart disease, or L-arginine 〔500 μg/(g·d)〕 was injected at the same time. Three weeks later, the changes of rat lung were observed under light and electric microscopy, and the changes of endothelial nitric oxide synthase(eNOS)in rat lung were measured by image analysis. Three weeks after MCT treatment, the expression of eNOS increased significantly in endothelia of lung vessels, on the contrarary, decreased evidently in bronchial epithelia as the experimental time passed by, and L-arginine could reduce the injury of lung induced by MCT. It showed that NO may play an important protective role during the process of pulmonary heart disease formed, the production of NO is not enough to resist the pulmonary vascular injury.

Key words: monocrotaline, pulmonary heart disease, nitric oxide, enzymes