Experimental study on the mechanism of protective effect of free Fu on gut-derived endotoxin-mediated lung damage

The effect of tumor necrosis factor-alpha (TNF-alpha) on endotoxin (ET)-mediated lung damage caused by incomplete ligation of large intestine and the influence of free Fu on the expression of TNF-alpha mRNA were explored. Forty SD rats were randomly divided into 4 groups: normal control group, model group, ligation group and treatment group (n =10 in each group). The models were made by the method of partly ligating the rectum outside the body. The plasma level of lipopolysaccaride was measured by dynamic nephelo metric method and the serum level of TNF-alpha was detected by the method of radioactive immunity. The expression of TNF-alpha mRNA in lung tissue was detected by RT-PCR method. The results were compared among the 4 groups. The results showed the plasma levels of ET and serum TNF-alpha in the model group and the expression of TNF-alpha mRNA in the lung tissues were remarkably higher than those in the normal control group (P<0.01). After the treatment of free Fu, all of the above indexes in the treatment group were all decreased as compared with model group (all P<0.01), and the damage to lung was alleviated. It was concluded that TNF-alpha might play a very important role in the ET-mediated lung damage caused by incomplete ligation of large intestine, free Fu could protect the lung from damage.