To observe the protective effect of takepron(lansoprazole)on the gastric mucosal lesion in rats and its mechanisms . Before gastric mucosal lesion was produced in rats with pure alcohol,takepron was administered into the gastric lumen, and Nω nitro L arginine methyl ester(L NAME) and L arginine were injected intravenously. Gastric mucosal blood flow(GMBF)was assessed with laser Doppler flowmetry,gastric mucosal and serum NO - 2 /NO - 3 were measured by cadmium granulation reduction and colorimetric method,and the gastric mucosal ulcer index(UI),the degree of tissue necrosis and neutrophil infiltration were observed . The results showed that UI of the takepron group was much lower than that of the control group( P <0.01),and the degree of tissue necrosis and neutrophil infiltration of the takepron group was much milder than that of the control group( P <0.01). The protective effect of takepron was significantly decreased with prior administration of L NAME.The inhibitory effect of L NAME was antagonized with prior administration of L arginine.Takepron administered directly into the gastric lumen obviously increased GMBF,and gastric mucosal and serum NO - 2 /NO - 3 . This effect was prevented by pretreatment with L NAME,but the antisecretory effect of takepron was not affected . The results suggest that takepron plays an important protective role in the gastric mucosal lesion in rats via the generation of nitric oxide,and there is no relation with antisecretory action of takepron.