Effect of propranolol on bacterial translocation in rats after major liver resection

Abstract

Objective To investigate the effects of propranolol on bacterial translocation in rats after major liver resection. Methods Forty five rats were randomly divided into three groups, sham operation group (SO group, n=15), 70% partial hepatectomy group (PH group, n=15) and 70% partial hepatectomy plus propranolol group(PHP group, n=15). The rats in SO group received gastric perfusion with 2 ml normal saline. The rats in the PH and PHP groups had 70% of their liver left and middle lobes resected. The rats in the PH group were given gastric perfusion of 2 ml normal saline and those in the PHP group were given gastric perfusion of 2 ml propranolol solution (5 mg/ml) after operation and the treatment was repeated 12 hours later. All rats underwent laparotomy 24 hours later after operation. Portal pressure, blood endotoxin and D-lactic acid were measured. Mesenteric lymph nodes were harvested for standard bacteriologic culture and characterization. Intestinal wall was resected for observing intestinal mucosal injury by light microscope and electron microscope. Bacterial translocation rate was calculated. The intestinal mucosal injury was graded. One-way analysis of variance and LSD-t test were used to compare the change of the portal pressure, blood endotoxin and D-lactic acid among 3 groups. Fisher definite probability method was used to compare the bacterial translocation rate. Kruskal-Wallis and Mann-Whitney test were used to compare the intestinal mucosal injury. Results The portal pressure of rats in the PH group rats (13.8±2.4)cm H2O was significantly higher compared with the SO(8.2±2.0)cm H2O and PHP group(10.8±2.4)cm H2O (t=6.84, 3.38; all in P<0.01). The blood endotoxin levels decreased significantly in the PHP (6.8±2.0)pg/ml and SO group groups (2.0±0.5)pg/ml compared with PH (13.7±4.1)pg/ml (t=9.44, 5.26; all in P<0.01). There were 1, 8, 3 rats with bacterial translocation in the SO, PH and PHP group with 53%,7%,20% of bacterial translocation rate respectively. There was significant difference in bacteria translocation rate between the PH group and the other groups(all in P<0.05). The bacteria culture showed that Escherichia coli were the main bacteria. D-lactic acid in the PH group rats (26±5)mg/ml was significantly higher compared with the SO(6±3) mg/ml and PHP(15±4)mg/ml group(t=13.08, 6.49; all in P<0.01). The median of intestinal mucosal injury scores was significantly higher in the PH group rats (5), compared with the SO(1) and PH (3)group (U=47.33, 38.64; all in P<0.01) . The intestinal mucosa of rats in the SO group was intact with continuous slime layer over the epithelial cells. On the contrary, the rats in the PH group had destroyed microvilli of different degree, focal damage, swollen or disappeared cellular mitochondria, degeneration of mitochondrial ridges and widened cell gaps. The damage degree of intestine mucosa in the PHP group was between the SO and PH group. Conclusions Propranolol can reduce the portal pressure, enhance the intestinal barrier function, diminish the bacterial translocation. Therefore, intragastric gavaging with propranolol can prevent the postoperative infection in rats undergoing major liver resection. Key words: Propranolol; Intestinal barrier; Major liver resection; Bacterial translocation; Endotoxin; Sprague-Dawley rats