bjectives. To investigate the role of endogenous heme oxygenase （HO）/carbon monoxide （CO） system in regulating the process of intussusception （IN） induced by administration of lipopolysaccharide （LPS） in rats. Methods. IN model of rats were induced by lipopolysaccharide. HO activity was determined by the amount of bilirubin formation which was measured with a doublebeam spectrophotometer

and HbCO formation was measured by COoximeter. Results. The results showed that LPS （10mg/kg） caused IN in up to 40% of the rats at 6h after treatment of LPS. The incidence of IN were significantly increased by 50% （P<005） and by 832%（P<001） in HO substrate（hemeLlysinate）treated rats and in exogenous COtreated rats

respectively; but it was significantly decreased by 418%（P<005） after administration of ZnDPBG

an inhibitor of heme oxygenase （HO） activity. Furthermore

LPS increased HO activity

HbCO formation cGMP content within colic smooth muscle and the plasma level of cGMP

and these parameters were significantly elevated by 626%（P<001）

400%（P<001）

493%（P<005） and 38%（P<005）

respectively

compared with LPSnonIN rats. Conclusion. It is suggested that endogenous HO/CO system plays an important role in the process of IN induced by LPS

and inhibition of HO activity may decrease the formation of IN.