title: Circulating nitrite contributes to cardioprotection by remote ischemic preconditioning.
abstract: BACKGROUND
  Remote ischemic preconditioning (rIPC) with short episodes of ischemia/reperfusion (I/R) of an organ remote from the heart is a powerful approach to protect against myocardial I/R injury. The signal transduction pathways for the cross talk between the remote site and the heart remain unclear in detail.
  
  
  OBJECTIVE
  To elucidate the role of circulating nitrite in cardioprotection by rIPC.
  
  
  RESULTS
  Mice were subjected to 4 cycles of no-flow ischemia with subsequent reactive hyperemia within the femoral region and underwent in vivo myocardial I/R (30 minutes/5 minutes or 24 hours). The mouse experiments were conducted using genetic and pharmacological approaches. Shear stress-dependent stimulation of endothelial nitric oxide synthase within the femoral artery during reactive hyperemia yielded substantial release of nitric oxide, subsequently oxidized to nitrite and transferred humorally to the myocardium. Within the heart, reduction of nitrite to nitric oxide by cardiac myoglobin and subsequent S-nitrosation of mitochondrial membrane proteins reduced mitochondrial respiration, reactive oxygen species formation, and myocardial infarct size. Pharmacological and genetic inhibition of nitric oxide/nitrite generation by endothelial nitric oxide synthase at the remote site or nitrite bioactivation by myoglobin within the target organ abrogated the cardioprotection by rIPC. Transfer experiments of plasma from healthy volunteers subjected to rIPC of the arm identified plasma nitrite as a cardioprotective agent in isolated Langendorff mouse heart preparations exposed to I/R.
  
  
  CONCLUSIONS
  Circulating nitrite derived from shear stress-dependent stimulation of endothelial nitric oxide synthase at the remote site of rIPC contributes to cardioprotection during I/R.
  
  
  BACKGROUND
  http://www.clinicaltrials.gov. Unique identifier: NCT01259739.
authors.affiliation: From the Department of Medicine, Division of Cardiology, Pulmonology and Vascular Medicine, Medical Faculty, University Hospital Duesseldorf, Duesseldorf, Germany (T.R., M.T., U.B.H.-C., M.K.); Department of Pharmacology and Chemical Biology, University of Pittsburgh, PA (S.S.); Institute for Pathophysiology, University of Essen, Essen, Germany (G.H.); and Cardiovascular Research Institute Duesseldorf, Duesseldorf, Germany (M.K.).
authors.forename: Tienush
authors.initials: T
authors.lastname: Rassaf
authors.forename: Matthias
authors.initials: M
authors.lastname: Totzeck
authors.forename: Ulrike B
authors.initials: UB
authors.lastname: Hendgen-Cotta
authors.forename: Sruti
authors.initials: S
authors.lastname: Shiva
authors.forename: Gerd
authors.initials: G
authors.lastname: Heusch
authors.forename: Malte
authors.initials: M
authors.lastname: Kelm
mesh_terms: D000818:Animals; D005542:Forearm / Q000098:blood supply; D006614:Hindlimb / Q000098:blood supply; D006801:Humans; D006940:Hyperemia / Q000097:blood; D019194:Ischemic Preconditioning / Q000379:methods*; D019157:Ischemic Preconditioning, Myocardial / Q000379:methods; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D017202:Myocardial Ischemia / Q000097:blood* / Q000503:physiopathology / Q000517:prevention & control*; D009569:Nitric Oxide / Q000097:blood; D052250:Nitric Oxide Synthase Type III / Q000097:blood*; D009573:Nitrites / Q000097:blood*; D033081:Shear Strength / Q000502:physiology
chemical_list: D009573:Nitrites; D009569:Nitric Oxide; D052250:Nitric Oxide Synthase Type III; C496315:Nos3 protein, mouse
keywords: myocardial; myoglobin; nitric oxide synthase type III