title: Nitric oxide: a mediator of endotoxin-induced middle ear effusions.
abstract: Using a rat model, the authors investigated the role of nitric oxide (NO) in endotoxin-induced middle ear effusion (MEE). After the eustachian tube was obstructed, the middle ear was transtympanically injected with 35 microL of either 1 mg/mL lipopolysaccharide (LPS) or LPS and 1 mmol/L N-nitro-L-arginine methyl ester (L-NAME), a competitive inhibitor of NO synthase. Over the next 6 hours, the fluid within the middle ear was collected every 2 hours, and the quantity of albumin in the fluid, an index of vascular leakage, was determined using enzyme-linked immunosorbent assay. L-NAME significantly reduced LPS-induced vascular extravasation into the middle ear. Inoculation of the ear with L-arginine, the substrate for NO synthase, reversed the effects of L-NAME. These results indicate that NO is a mediator of LPS-induced MEE. Therefore, inhibition of NO synthase may represent a novel approach to the treatment of otitis media with effusion.
authors.affiliation: Ohio State University College of Medicine, Columbus, USA.
authors.forename: S S
authors.initials: SS
authors.lastname: Ball
authors.forename: J
authors.initials: J
authors.lastname: Prazma
authors.forename: D
authors.initials: D
authors.lastname: Dais
authors.forename: K W
authors.initials: KW
authors.lastname: Rosbe
authors.forename: H C
authors.initials: HC
authors.lastname: Pillsbury
mesh_terms: D000418:Albumins / Q000032:analysis; D000818:Animals; D001120:Arginine / Q000008:administration & dosage / Q000031:analogs & derivatives*; D004791:Enzyme Inhibitors / Q000008:administration & dosage*; D004797:Enzyme-Linked Immunosorbent Assay; D008070:Lipopolysaccharides / Q000008:administration & dosage*; D019331:NG-Nitroarginine Methyl Ester; D009569:Nitric Oxide / Q000502:physiology*; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors*; D010034:Otitis Media with Effusion / Q000188:drug therapy* / Q000473:pathology / Q000503:physiopathology*; D051381:Rats; D013997:Time Factors
chemical_list: D000418:Albumins; D004791:Enzyme Inhibitors; D008070:Lipopolysaccharides; D009569:Nitric Oxide; D001120:Arginine; D019001:Nitric Oxide Synthase; D019331:NG-Nitroarginine Methyl Ester