title: Human blood platelets lack nitric oxide synthase activity.
abstract: Reports on expression and functionality of nitric oxide synthase (NOS) activity in human blood platelets and erythrocytes are contradictory. We used a specific gas chromatography-mass spectrometry (GC-MS) method to detect NOS activity in human platelets. The method measures simultaneously [(15)N]nitrite and [(15)N]nitrate formed from oxidized (15)N-labeled nitric oxide ((15)NO) upon its NOS-catalyzed formation from the substrate l-[guanidino-(15)N2]-arginine. Using this GC-MS assay, we did not detect functional NOS in non-stimulated platelets and in intact platelets activated by various agonists (adenosine diphosphate, collagen, thrombin, or von Willebrand factor) or lysed platelets. l-[guanidino-nitro]-Arginine-inhibitable NOS activity was measured after addition of recombinant human endothelial NOS to lysed platelets. Previous and recent studies from our group challenge expression and functionality of NOS in human platelets and erythrocytes.
authors.affiliation: Hannover Medical School, Institute of Clinical Pharmacology , Hannover , Germany .
authors.forename: Anke
authors.initials: A
authors.lastname: Böhmer
authors.forename: Stepan
authors.initials: S
authors.lastname: Gambaryan
authors.forename: Dimitrios
authors.initials: D
authors.lastname: Tsikas
mesh_terms: D000925:Anticoagulants / Q000494:pharmacology; D001792:Blood Platelets / Q000187:drug effects / Q000378:metabolism*; D004789:Enzyme Activation; D005260:Female; D008401:Gas Chromatography-Mass Spectrometry; D064368:Healthy Volunteers; D006801:Humans; D008297:Male; D019001:Nitric Oxide Synthase / Q000378:metabolism*; D052247:Nitric Oxide Synthase Type II / Q000378:metabolism; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism
chemical_list: D000925:Anticoagulants; D011994:Recombinant Proteins; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; D052250:Nitric Oxide Synthase Type III
keywords: Enzyme activity assays; mass spectrometry; nitric oxide; stable isotopes