title: Artery-to-vein differences in nitric oxide metabolites are diminished in sepsis.
abstract: OBJECTIVE
  Nitric oxide deficiency may contribute to microvascular dysfunction in sepsis. Current physiologic paradigms contend that nitrite and/or S-nitrosohemoglobin mediate intravascular delivery of nitric oxide. These nitric oxide metabolites are purportedly consumed during hemoglobin deoxygenation, producing nitric oxide and coupling intravascular nitric oxide delivery with metabolic demand. Systemic nitrite and S-nitrosohemoglobin consumption can be assessed by comparing their concentrations in arterial vs. venous blood. We hypothesized that arterial vs. venous differences in nitrite and S-nitrosohemoglobin are diminished in sepsis and associated with mortality.
  
  
  METHODS
  Case-control and prospective cohort study.
  
  
  METHODS
  Adult intensive care units of an academic medical center.
  
  
  METHODS
  Eighty-seven critically ill septic patients and 52 control subjects.
  
  
  METHODS
  None.
  
  
  RESULTS
  Nitrite and S-nitrosohemoglobin were measured using tri-iodide-based reductive chemiluminescence. In control subjects, arterial plasma, whole blood, and red blood cell nitrite levels were higher than the corresponding venous levels. In contrast, S-nitrosohemoglobin was higher in venous compared to arterial blood. In septic patients, arterial vs. venous red blood cell nitrite and S-nitrosohemoglobin differences were absent. Furthermore, the plasma nitrite arterial vs. venous difference was absent in nonsurvivors.
  
  
  CONCLUSIONS
  In health, nitrite levels are higher in arterial vs. venous blood (suggesting systemic nitrite consumption), whereas S-nitrosohemoglobin levels are higher in venous vs. arterial blood (suggesting systemic S-nitrosohemoglobin production). These arterial vs. venous differences are diminished in sepsis, and diminished arterial vs. venous plasma nitrite differences are associated with mortality. These data suggest pathologic disruption of systemic nitrite utilization in sepsis.
authors.affiliation: Departments of Medicine, University of Rochester Medical Center, Rochester, NY, USA.
authors.forename: Mary Anne M
authors.initials: MA
authors.lastname: Morgan
authors.forename: Lauren M
authors.initials: LM
authors.lastname: Frasier
authors.forename: Judith C
authors.initials: JC
authors.lastname: Stewart
authors.forename: Cynthia M
authors.initials: CM
authors.lastname: Mack
authors.forename: Michael S
authors.initials: MS
authors.lastname: Gough
authors.forename: Brian T
authors.initials: BT
authors.lastname: Graves
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Apostolakos
authors.forename: Kathleen P
authors.initials: KP
authors.lastname: Doolin
authors.forename: Denise C
authors.initials: DC
authors.lastname: Darling
authors.forename: Mark W
authors.initials: MW
authors.lastname: Frampton
authors.forename: Anthony P
authors.initials: AP
authors.lastname: Pietropaoli
mesh_terms: D000367:Age Factors; D000368:Aged; D001158:Arteries / Q000378:metabolism* / Q000503:physiopathology; D016022:Case-Control Studies; D015331:Cohort Studies; D005260:Female; D006454:Hemoglobins / Q000032:analysis; D017052:Hospital Mortality; D006801:Humans; D008163:Luminescent Measurements; D008297:Male; D008875:Middle Aged; D009569:Nitric Oxide / Q000097:blood / Q000378:metabolism*; D009573:Nitrites / Q000097:blood; D011446:Prospective Studies; D018805:Sepsis / Q000097:blood* / Q000401:mortality / Q000503:physiopathology; D014680:Veins / Q000378:metabolism* / Q000503:physiopathology
chemical_list: D006454:Hemoglobins; D009573:Nitrites; C103574:S-nitrosohemoglobin; D009569:Nitric Oxide