Influence of epinephrine and norepinephrine on intestinal villous blood flow during endotoxemia

Abstract

Purpose: The objective of this study was to determine the effects of epinephrine and norepinephrine on mucosal villous blood flow in a normotensive model of endotoxemia. Materials and Methods: Thirty-two anesthetized rats were laparotomized, and a jejunal portion was exteriorized and opened by an antimesenteric incision. The jejunal segment was fixed on a plexiglass stage with the mucosal surface upward. Microcirculatory parameters were assessed by intravital videomicroscopy. The animals were randomly assigned to receive one of four treatments: infusion of Escherichia coli lipopolysaccharides (LPS, 2 mg/kg/h) without catecholamine pretreatment (LPS group); or infusion of LPS with epinephrine pretreatment (0.2 μg/kg/min, start 30 minutes before LPS infusion) (E group), or infusion of LPS with norepinephrine pretreatment (0.2 μg/kg/min, start 30 minutes before LPS infusion) (NE group). The control group did not receive either catecholamines or LPS. Mean diameter of central arterioles (D A) and mean erythrocyte velocity within the arterioles (V E) were measured 30 minutes before and at 0, 60, and 120 minutes after induction of endotoxemia. Mucosal villous blood flow was calculated from D A and V E. Results: LPS infusion alone and norepinephrine plus LPS infusion led to a significant vasoconstriction of central arterioles, which was associated with a similar decrease in mucosal villous blood flow. Epinephrine infusion alone led to a vasodilation and an increase in villous blood flow within the first 30 minutes. After induction of endotoxemia, D A returned to baseline values and villous blood flow was as low as in the LPS and the norepinephrine group after 120 minutes. Conclusion: In this experimental rat model, the catecholamines epinephrine and norepinephrine in a dosage of 0.2 μg-kg −-·min −1 neither diminish nor improve mucosal villous blood flow during the early phase of endotoxemia.