Effects Of Lipo-PGE₁ On Intestinal Microcirculation And Their Mechanisms During Acute Intestinal Venous Congestion Reperfusion In Rats

Objective: This study is to investigate the changes in intestinal microcirculation during acute intestinal injury that induced by venous congestion reperfusion, the effects of Lipo-PGE1 on the microcirculation changes and their possible mechanisms. Methods: 30 SD rats were divided into three groups, the acute intestinal venous congestion reperfusion group (CR group), the Lipo-PGE1 treatment group (Lipo-PGE1 group) and the sham operation group (SO group). To induce intestinal venous congestion reperfusion model, portal vein was clamped for 45 min, then unclamped for 60 min. This reperfusion model was made in CR group and in Lipo-PGE1 group. In Lipo-PGE1 group, 0.2μg Lipo-PGE1 was infused via veins 10 min before, just at clamping portal vein and 10 min after reperfusion respectively. The small intestine 2cm beyond the ileocecal junction and its mesenteric area was selected to be studied. Intestinal microcirculation was randomly observed in10 microscopic areas with a special device. The numbers of total capillary vessels and the vessels with active blood flow were recorded. Then the reperfusion rate could be calculated. Hemorrhagic spots around the capillary were recorded. Intestinal species were obtained at the end of the experiment for histological examination. The intestine injury was studied with Chiu's Grade classification. The mRNA expression of ICAM-1 and its protein expression in intestinal tissue were detected with Rt-PCR and immunohistology respectively. The GMP140 concentration in plasm was confined by radioimmunoassay. Results: In CR group, the microcirculation reperfusion rates were much lower (p<0.01) and the numbers of hemorrhagic spots around the capillary were much more than those in SO group (p<0.01). In Lipo-PGE1 group, however, the microcirculation reperfusion rates were much higher than those in CR group[(37.13±11.86)% vs (26.53±4.199)%,p<0.05], while no significant difference was found in hemorrhagic spots between the two groups. In CR group, optical microscopy showed that the intestine mucosa lesion was worse than normal with Chiu's Grade standard (p<0.05). But compared with CR group, it showed that intestine mucosa lesion was attenuated in Lipo-PGE1 group (p<0.05). GMP140 level in plasm (p<0.05), intestinal ICAM-1 mRNA/GAPDH ratio in CR group (p<0.01) and ICAM-1 expression of intestinal tissue were obviously higher than those in SO group (p<0.05). In Lipo-PGE1 group, GMP140 levels in plasm (26.70±4.620 vs 23.30±4.373, p<0.05), intestinal ICAM-1 mRNA/GAPDH ratio (0.8594±0.0836vs 0.9477±0.0962, p<0.05) and ICAM-1 expression of intestinal tissue were much lower than those in CR group (p<0.05).Conclusion: Intestinal open microcirculation decreased during acute intestinal venous congestion reperfusion. Lipo-PGE1 could protect effectively microcirculation and the injury caused by acute intestinal venous congestion reperfusion. These results implicated that the Lipo-PGE1 might on one hand suppress the activity of platelets, and on the other hand reduce the upregulation of ICAM-1 expression in intestinal tissue to prevent PMN from sticking to the vascular endothelial.