title: Nitric oxide inhalation inhibits platelet aggregation and platelet-mediated pulmonary thrombosis in rats.
abstract: Endothelium-derived nitric oxide (NO) inhibits in vitro platelet aggregation via a cGMP-dependent mechanism. The effect of inhaled NO on platelet-mediated pulmonary thrombosis following intravenous thrombotic challenge with collagen was examined in rats and compared with the effect of G4120, a cyclic Arg-Gly-Asp-containing synthetic pentapeptide that binds to the platelet glycoprotein IIb/IIIa receptor. Intraplatelet cGMP dose-dependently increased from 39 +/- 6 fmol/10(8) platelets in control to 46 +/- 6, 68 +/- 13, and 81 +/- 13 fmol/10(8) platelets after inhalation with 20, 40, and 80 ppm NO, respectively (P < .05 for 40 and 80 ppm). Ex vivo platelet aggregation of platelet-rich plasma induced by 1 microgram/mL collagen was reduced from 75 +/- 4% in control rats to 22 +/- 10% and 20 +/- 7% in rats ventilated with 40 and 80 ppm NO, respectively, and to 30 +/- 9% in G4120-treated rats (each P < .05 versus control). Circulating platelet counts 3 minutes after collagen injection were significantly higher in the inhaled NO and G4120 groups compared with control rats (250,000 +/- 18,000 and 223,000 +/- 10,000/microL versus 160,000 +/- 18,000/microL, each P < .05). The rise in pulmonary arterial pressure after collagen injection was significantly reduced in NO- and G4120-treated rats (26 +/- 1 and 27 +/- 1 versus 32 +/- 1 mm Hg in control rats, each P < .05). The number of pulmonary resistance vessels containing platelet thrombi was significantly smaller after inhaled NO and G4120 treatment compared with control (56 +/- 3% and 50 +/- 3% versus 68 +/- 3%, respectively; P < .05). Thus, NO inhalation reduces in vivo activation of circulating platelets and platelet-rich thrombosis in thromboembolic pulmonary hypertension. Inhalation of NO may be useful in cardiovascular diseases associated with platelet activation.
authors.affiliation: Center for Transgene Technology and Gene Therapy, Flanders Interuniversity Institute for Biotechnology, Leuven, Belgium.
authors.forename: Z
authors.initials: Z
authors.lastname: Nong
authors.forename: M
authors.initials: M
authors.lastname: Hoylaerts
authors.forename: N
authors.initials: N
authors.lastname: Van Pelt
authors.forename: D
authors.initials: D
authors.lastname: Collen
authors.forename: S
authors.initials: S
authors.lastname: Janssens
mesh_terms: D000280:Administration, Inhalation; D000818:Animals; D001792:Blood Platelets / Q000187:drug effects; D008297:Male; D009569:Nitric Oxide / Q000008:administration & dosage*; D010974:Platelet Aggregation / Q000187:drug effects*; D010975:Platelet Aggregation Inhibitors / Q000008:administration & dosage*; D011655:Pulmonary Embolism / Q000097:blood* / Q000503:physiopathology / Q000517:prevention & control*; D051381:Rats; D017208:Rats, Wistar
chemical_list: D010975:Platelet Aggregation Inhibitors; D009569:Nitric Oxide