title: Endothelial nitric oxide synthase mediates the cerebrovascular effects of erythropoietin in traumatic brain injury.
abstract: BACKGROUND
  Erythropoietin (Epo) improves post-traumatic cerebral blood flow (CBF), pressure autoregulation, and vascular reactivity to l-arginine. This study examines the dependence of these cerebral hemodynamic effects of Epo on nitric oxide generated by endothelial nitric oxide synthase (eNOS).
  
  
  METHODS
  Using laser Doppler flow imaging, CBF was monitored in wild-type (WT) and eNOS-deficient mice undergoing controlled cortical impact followed by administration of Epo (5000 U/kg) or normal saline.
  
  
  RESULTS
  Cerebral blood flow decreased in all groups post-injury with the greatest reductions occurring at the impact site. Epo administration resulted in significantly higher CBF in the peri-contusional sites in the WT mice [70.2 ± 3.35% in Epo-treated compared to 53 ± 3.3% of baseline in saline-treated mice (p < 0.0001)], but no effect was seen in the eNOS-deficient mice. No CBF differences were found at the core impact site where CBF dropped to 20-25% of baseline in all groups.
  
  
  CONCLUSIONS
  These differences between eNOS-deficient and WT mice indicate that the Epo mediated improvement in CBF in traumatic brain injury is eNOS dependent.
authors.affiliation: Department of Neurosurgery, Baylor College of Medicine , Houston, TX , USA.
authors.forename: Jovany
authors.initials: J
authors.lastname: Cruz Navarro
authors.affiliation: Department of Neurosurgery, Baylor College of Medicine , Houston, TX , USA.
authors.forename: Shibu
authors.initials: S
authors.lastname: Pillai
authors.affiliation: Department of Neurosurgery, Baylor College of Medicine , Houston, TX , USA.
authors.forename: Lucido L
authors.initials: LL
authors.lastname: Ponce
authors.affiliation: Department of Neurosurgery, Baylor College of Medicine , Houston, TX , USA.
authors.forename: Mai
authors.initials: M
authors.lastname: Van
authors.affiliation: Department of Pathology and Immunology, Baylor College of Medicine , Houston, TX , USA ; Department of Neurology, Baylor College of Medicine , Houston, TX , USA.
authors.forename: Jerry Clay
authors.initials: JC
authors.lastname: Goodman
authors.affiliation: Department of Neurosurgery, Baylor College of Medicine , Houston, TX , USA.
authors.forename: Claudia S
authors.initials: CS
authors.lastname: Robertson
keywords: cerebral blood flow; erythropoietin; neuroprotection; nitric oxide; nitric oxide synthase; traumatic brain injury