| Objective The purpose of this study was to investigate the effects of abdominal irrigation with PVPI on intestinal epithelial barrier in a colorectal cancer-induced rat model.Methods 24 male SD rats aged 5 weeks made rat model of colorectal cancer.All rats were injected intraperitoneally with a single dose(15mg.kg-1)of azoxymethan(AOM)followed by three cycles of DSS in drinking water for 1 week and normal drinking water for 2 weeks.They were randomly divided into three groups(n = 8): sham group(group S),0.9% saline solution(group N),povidone-iodine(group P).After anesthesia,rats were made abdominal median incision without futher treatment.In group N,peritoneal lavage through median laparotomywas performed with 0.9% saline solution 7m L·kg-1.In group P,peritoneal lavage through median laparotomy was performed with 0.45%～0.55% povidone-iodine 7m L·kg-1.Animals were monitored for carotid artery pressure.MAP and HR were recorded before peritoneal lavage(T0)and 5 minutes(T1),10 minutes(T2),15 minutes(T3),20 minutes(T4),25 minutes(T5)and 30 minutes(T6)after peritoneal lavage.Carotid blood was used for blood gas analysis at the baseline and 30 minutes after peritoneal lavage.Before irrigation and 30 minutes after irrigation,the peritoneal fluid was sampled to calculate the protein concentration.The plasma from portal vein(1ml)was assayed for the concentration of D-lactate and endotoxin.Small intestinal mucosal tissues were obtained to observe the and ultrastructural changes by the electron microscope.Results There were no significant difference in MAP and HR among three groups at the baseline(T0),(P>0.05).Compred with basal level(T0),The MAP and HR in group S and group N have no statistical differences at T1~T6(P>0.05),and the MAP an d HR were lower than basal level(T0)after peritoneal lavage with povidone-iodine at T1~T6(P>0.05).After the lavage administration,the MAP and HR of the PVPI-treated rats was significantly lower than those of the control group and the NS-treated rats at all time points(T1~T6).There were no significant differences in values of p H,BE,HCO3-,or lactic acid among three groups at the baseline(T0).To compred with basal level(T0),values of p H,BE,HCO3-,and lactic acid in group P were significantly decreased 30 minutes after the lavage administration and the lactic acid content was significantly higher(P>0.05).The values of p H,BE,and HCO3-were significantly decreased 30 minutes after peritoneal lavage with PVPI compared with the sham and N group(Table 1).Moreover,the lactic acid content was significantly higher in the group P than that in the group S and the group N.The protein concentration in peritoneal fluid after lavage was significantly higher in the group P than that in the group N.Compared with group S,the protein concentration was significantly decreased in the group N.Peritoneal lavage with povidone-iodine resulted in significantly higher levels of endotoxin and D-lactate compared with the group S and group N.In the group S,the TJ were intact and clear between the adjoining cells and epithelial cell surface microvilli were arranged in neat rows.In saline solution-treated rats,the TJ and microvilli morphology underwent no observable changes,remaining similar to the sham group.After PVPI treatment,TJs were obscured or disappeared.Moreover,the paracellular spaces were wider.The microvilli were damaged and sparse with irregular length and arrangement.Conclusion Peritoneal lavage with povidone-iodine may cause hemodynamic fluctuations,lactic acidosis and endotoxic shockin by compromising the integrity of the intestinal mucosal barrier and increasing the permeability of intestinal epithelium in colorectal cancer rats. |
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