AIM: To test the ability of penehyclidine hydrochloride (PHC) to attenuate intestinal injury in a rat cardiopulmonary bypass (CPB) model. METHODS: Male Sprague-Dawley rats were randomly divided into six groups (eight each): sham-operated control; sham-operated low-dose PHC control (0.6 mg/kg); sham-operated high-dose PHC control (2.0 ring/kg); CPB vehicle control; CPB low-dose PHC (0.6 mg/kg); and CPB high-dose PHC (2.0 mg/kg). Blood samples were collected from the femoral artery 2 h after CPB for determination of plasma diamine oxidase (DAO), D-lactate and endotoxin levels. Spleen, liver, mesenteric lymph nodes and lung were removed for biochemical analyses. Intestinal tissue ultrastructure was examined by electron microscopy. RESULTS: In the sham-operated groups, high- and low-dose-PHC had no significant impact on the levels of DAO, D-lactate and endotoxin, or the incidence of intestinal bacterial translocation (BT). Serum levels of DAO, D-lactate, endotoxin and the incidence of intestinal BT were significantly increased in the surgical groups, compared with the sham-operated groups (0.543 +/- 0.061, 5.697 +/- 0.272, 14.75 +/- 2.46, and 0/40 vs 1.038 +/- 0.252, 9.377 +/- 0.769, 60.37 +/- 5.63, and 30/40, respectively, all P < 0.05). PHC alleviated the biochemical and histopathological changes in a dose-dependent manner. Serum levels of DAO, D-lactate, and endotoxin and the incidence of intestinal BT in the high-dose PHC group were significantly lower than in the low-dose PHC group (0.637 +/- 0.064, 6.972 +/- 0.349, 29.64 +/- 5.49, and 14/40 vs 0.998 +/- 0.062, 7.835 +/- 0.330, 38.56 +/- 4.28, and 6/40, respectively, all P < 0.05). CONCLUSION: PHC protects the structure and function of the intestinal mucosa from injury after CPB in rats. (C) 2011 Baishideng. All rights reserved.