title: Activated protein C improves pial microcirculation in experimental endotoxemia in rats.
abstract: BACKGROUND
  The brain is one of the first organs affected clinically in sepsis. Microcirculatory alterations are suggested to be a critical component in the pathophysiology of sepsis. The aim of this study was to investigate the effects of recombinant human activated protein C (rhAPC) on the pial microcirculation in experimental endotoxemia using intravital microscopy. Our hypothesis is rhAPC protects pial microcirculation in endotoxemia.
  
  
  METHODS
  Endotoxemia was generated in Lewis rats with intravenous injection of lipopolysaccharide (LPS, 5 mg/kg i.v.). Dura mater was removed through a cranial window to expose pial vessels on the brain surface. The microcirculation, including leukocyte-endothelial interaction, functional capillary density (FCD) and plasma extravasation of pial vessels was examined by fluorescent intravital microscopy (IVM) 2 h after administration of LPS, LPS and rhAPC or equivalent amount of saline (used as Control group). Plasma cytokine levels of interleukin 1 alpha (IL1-α), tumor necrosis factor-α (TNF-α), interferon γ (IFN-γ), Monocyte chemotactic protein-1 (MCP-1) and Granulocyte-macrophage colony-stimulating factor (GM-CSF) were evaluated after IVM.
  
  
  RESULTS
  LPS challenge significantly increased leukocyte adhesion (773±190 vs. 592±152 n/mm(2) Control), decreased FCD (218±54 vs. 418±74 cm/cm(2) Control) and increased proinflammatory cytokine levels (IL-1α: 5032±1502 vs. 8±21 pg/ml; TNF-α: 1823±1007 vs. 168±228 pg/ml; IFN-γ: 785±434 vs. 0 pg/ml; GM-CSF: 54±52 vs. 1±3 pg/ml) compared to control animals. rhAPC treatment significantly reduced leukocyte adhesion (599±111 n/mm(2)), increased FCD (516±118 cm/cm(2)) and reduced IL-1α levels (2134±937 pg/ml) in the endotoxemic rats.
  
  
  CONCLUSIONS
  APC treatment significantly improves pial microcirculation by reducing leukocyte adhesion and increasing FCD.
authors.affiliation: Department of Anesthesia, Dalhousie University, Halifax, NS, Canada.
authors.forename: Juan
authors.initials: J
authors.lastname: Zhou
authors.forename: Dragan
authors.initials: D
authors.lastname: Pavlovic
authors.forename: Julia
authors.initials: J
authors.lastname: Willecke
authors.forename: Claudius
authors.initials: C
authors.lastname: Friedel
authors.forename: Sara
authors.initials: S
authors.lastname: Whynot
authors.forename: Orlando
authors.initials: O
authors.lastname: Hung
authors.forename: Vladimir
authors.initials: V
authors.lastname: Cerny
authors.forename: Henry
authors.initials: H
authors.lastname: Schroeder
authors.forename: Michael
authors.initials: M
authors.lastname: Wendt
authors.forename: Romesh
authors.initials: R
authors.lastname: Shukla
authors.forename: Christian
authors.initials: C
authors.lastname: Lehmann
mesh_terms: D000818:Animals; D002448:Cell Adhesion; D002550:Cerebral Veins / Q000473:pathology*; D016207:Cytokines / Q000378:metabolism; D019446:Endotoxemia / Q000378:metabolism*; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000378:metabolism; D007962:Leukocytes / Q000166:cytology; D008070:Lipopolysaccharides / Q000378:metabolism; D008833:Microcirculation; D008853:Microscopy / Q000379:methods; D010841:Pia Mater / Q000098:blood supply*; D011486:Protein C / Q000378:metabolism*; D051381:Rats; D011917:Rats, Inbred Lew; D011994:Recombinant Proteins / Q000378:metabolism; D018805:Sepsis; D013997:Time Factors
chemical_list: D016207:Cytokines; D008070:Lipopolysaccharides; D011486:Protein C; D011994:Recombinant Proteins; D016178:Granulocyte-Macrophage Colony-Stimulating Factor