Research

Activated protein C improves intestinal microcirculation in experimental endotoxaemia in the rat

Christian Lehmann¹ , Konrad Meissner² , Andreas Knöck¹ , Stephan Diedrich¹ , Dragan Pavlovic¹ , Matthias Gründling¹ , Taras Usichenko¹ , Michael Wendt¹ and Jürgen Birnbaum³

¹Klinik und Poliklinik für Anästhesiologie und Intensivmedizin, Ernst Moritz Arndt University, Fr.-Loeffler-Str. 23a, D-17475 Greifswald, Germany

²Washington University Medical Center, Department of Anesthesiology, 660 S. Euclid Ave., St. Louis, MO 63110, USA

³Charité – Universitätsmedizin Berlin, Kliniken für Anästhesiologie und operative Intensivmedizin, Campus Charité Mitte, Charitéplatz 1, D-10117 Berlin, Germany

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Critical Care 2006, 10:R157doi:10.1186/cc5093

Published:	13 November 2006

Abstract

Introduction

Successful treatment of severe sepsis and septic shock remains a major challenge in critical care medicine. The recently introduced recombinant human activated protein C (APC) remarkably improved the outcome of septic patients. The influence of APC on intestinal circulation is still poorly understood. Therefore, the present study aimed to investigate the effects of APC on intestinal microcirculation during experimental endotoxaemia in rats by using intravital microscopy.

Methods

A total of 44 male Lewis rats were randomly assigned to receive intravenous injections of 15 mg/kg lipopolysaccharide alone (LPS) (n = 11) or LPS followed by subsequent injection of 2 mg/kg recombinant human APC (LPS + APC) (n = 11), whereas control animals received either APC (n = 11) or saline (n = 11). Animals underwent observations of functional capillary density and leucocyte adherence on venular endothelium in the microcirculation of the intestinal wall by means of intravital fluorescence microscopy. Indicators of macrocirculation as well as plasma levels of tumour necrosis factor-α, interleukin (IL)-1β, IL-6, and IL-10 were measured.

Results

Although APC administration of both LPS-treated and control rats did not change macrocirculation or release of inflammatory cytokines, it increased mucosal and muscular functional capillary density (p < 0.001 and p < 0.05, respectively) and reduced the number of firmly adhering leucocytes in intestinal submucosal V1 and V3 venules (p < 0.01) in LPS + APC-treated compared with LPS-treated animals, which did not receive APC. No remarkable differences that could be attributed to APC treatment were observed between the two control groups.

Conclusion

APC administration during experimental endotoxaemia improved intestinal microcirculation by protecting functional capillary density as a measure of microvascular perfusion and exerted anti-inflammatory effects by reducing leucocyte adherence to the endothelium in submucosal venules. Therefore, beneficial effects of APC in septic patients might be due, in part, to improved intestinal microcirculation.