Effects of iloprost, a stable prostacyclin analog, on intestinal leukocyte adherence and microvascular blood flow in rat experimental endotoxemia

Objective: To investigate the effects of iloprost, a stable prostacyclin analog, on leukocyte adherence in intestinal venules and intestinal microvascular blood flow in experimental endotoxemia. Design: Prospective, randomized, controlled animal study. Setting: Experimental laboratory. Subjects: Twenty-one male Wistar rats weighing 190 ± 40 g. Interventions: The rats were divided equally into three groups: the first was a control group; the second received endotoxin (20 mg/kg lipopolysaccharide from Escherichia coli 055:B5 intravenously); and the third received endotoxin and intravenous iloprost infusion (2 ng·kg^-1·min^-1). Measurements and Main Results: The distal small intestine of the animals was examined by using intravital fluorescence video-microscopy 2 hrs after endotoxin challenge. Leukocytes were stained in vivo by means of rhodamine 6G. Intestinal microvascular blood flow was measured by laser Doppler flowmetry in the terminal ileum. Iloprost treatment significantly attenuated the count of adherent leukocytes in collecting venules (control, 61 ± 10 n/mm²; lipopolysaccharide, 364 ± 60 n/mm²; iloprost, 232 ± 29 n/mm²; p < .05) and in postcapillary venules (control, 96 ± 14 n/mm²; lipopolysaccharide, 470 ± 21 n/mm²; iloprost 390 ± 41 n/mm²; p < .05). Intestinal microvascular blood flow was decreased significantly in the lipopolysaccharide group (-49%), whereas iloprost-treated animals showed no significant difference compared with the control group. Conclusions: The study demonstrated that administration of iloprost attenuated leukocyte adherence in postcapillary and collecting intestinal venules and improved intestinal microvascular blood flow. Thus, iloprost treatment may impact endotoxin-induced intestinal injury.