title: Neurotrophins induce nitric oxide generation in human pulmonary artery endothelial cells.
abstract: OBJECTIVE
  Members of the growth factor family of neurotrophins [NTs; e.g. brain-derived neurotrophic factor (BDNF), neurotrophin-3 (NT3)] and their high-affinity receptors (tropomyosin-related kinase; Trk) and low-affinity receptors p75 neurotrophin receptor (p75NTR) have been localized to pulmonary artery (PA) in humans. However, their role is unclear. Based on previous findings of NTs and their receptors within the pulmonary endothelium, we tested the hypothesis that NTs induce nitric oxide (NO) production in pulmonary endothelial cells (ECs), thus contributing to vasodilation.
  
  
  RESULTS
  In human pulmonary artery ECs loaded with the NO-sensitive fluorescent dye diaminofluorescein-2, both BDNF and NT3 (100 pM, 1 nM, and 10 nM) acutely (<10 min) and substantially increased fluorescence levels in a concentration-dependent fashion (to levels comparable to that induced by 1 μM acetylcholine). NT-induced elevation of NO levels was blunted by the tyrosine kinase inhibitor K252a, the nitric oxide synthase (NOS) inhibitor N(G)-nitro-L-arginine methyl ester, the Ca(2+) chelator 1,2-bis(o-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid, and the NO scavenger 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide. Suppression of TrkB or TrkC expression via siRNA as well as functional blockade of p75NTR prevented NT-induced NO elevation. Both BDNF and NT3 increased phosphorylation of Akt and endothelial NO synthase (eNOS). In endothelium-intact porcine PA rings, NTs increased cGMP and induced vasodilation in pre-contracted arteries.
  
  
  CONCLUSIONS
  These results indicate that NTs acutely modulate pulmonary endothelial NO production and contribute to relaxation of the pulmonary vasculature.
authors.affiliation: Department of Physiology, Mayo Clinic College of Medicine, 4-184 W. Jos SMH, Rochester, MN 55905, USA.
authors.forename: Lucas W
authors.initials: LW
authors.lastname: Meuchel
authors.forename: Michael A
authors.initials: MA
authors.lastname: Thompson
authors.forename: Steven D
authors.initials: SD
authors.lastname: Cassivi
authors.forename: Christina M
authors.initials: CM
authors.lastname: Pabelick
authors.forename: Y S
authors.initials: YS
authors.lastname: Prakash
mesh_terms: D000109:Acetylcholine / Q000494:pharmacology; D019208:Brain-Derived Neurotrophic Factor / Q000494:pharmacology*; D002478:Cells, Cultured; D042783:Endothelial Cells / Q000378:metabolism*; D006801:Humans; D020933:Neurotrophin 3 / Q000494:pharmacology*; D009569:Nitric Oxide / Q000096:biosynthesis*; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism; D010766:Phosphorylation; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D011651:Pulmonary Artery / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000235:genetics; D020800:Receptor, Nerve Growth Factor / Q000502:physiology; D020813:Receptor, trkB / Q000502:physiology
chemical_list: D019208:Brain-Derived Neurotrophic Factor; D020933:Neurotrophin 3; D034741:RNA, Small Interfering; D020800:Receptor, Nerve Growth Factor; D009569:Nitric Oxide; D052250:Nitric Oxide Synthase Type III; D020813:Receptor, trkB; D051057:Proto-Oncogene Proteins c-akt; D000109:Acetylcholine