title: Expression of nitric oxide synthase-2 in the lungs decreases airway resistance and responsiveness.
abstract: Individuals with asthma have increased levels of nitric oxide in their exhaled air. To explore its role, we have developed a regulatable transgenic mouse capable of overexpressing inducible nitric oxide synthase in a lung-specific fashion. The CC10-rtTA-NOS-2 mouse contains two transgenes, a reverse tetracycline transactivator under the control of the Clara cell protein promoter and the mouse nitric oxide synthase-2 (NOS-2) coding region under control of a tetracycline operator. Addition of doxycycline to the drinking water of CC10-rtTA-NOS-2 mice causes an increase in nitric oxide synthase-2 that is largely confined to the airway epithelium. The fraction of expired nitric oxide increases over the first 24 h from approximately 10 parts per billion to a plateau of approximately 20 parts per billion. There were no obvious differences between CC10-rtTA-NOS-2 mice, with or without doxycycline, and wild-type mice in lung histology, bronchoalveolar protein, total cell count, or count differentials. However, airway resistance was lower in CC10-rtTA-NOS-2 mice with doxycycline than in CC10-rtTA-NOS-2 mice without doxycycline or wild-type mice with doxycycline. Moreover, doxycycline-treated CC10-rtTA-NOS-2 mice were hyporesponsive to methacholine compared with other groups. These data suggest that increased nitric oxide in the airways has no proinflammatory effects per se and may have beneficial effects on pulmonary function.
authors.affiliation: Department of Environmental Health, Harvard School of Public Health, Boston, MA 02115-6021, USA.
authors.forename: Josephine
authors.initials: J
authors.lastname: Hjoberg
authors.forename: Stephanie
authors.initials: S
authors.lastname: Shore
authors.forename: Lester
authors.initials: L
authors.lastname: Kobzik
authors.forename: Shoji
authors.initials: S
authors.lastname: Okinaga
authors.forename: Arlene
authors.initials: A
authors.lastname: Hallock
authors.forename: Joseph
authors.initials: J
authors.lastname: Vallone
authors.forename: Venkat
authors.initials: V
authors.lastname: Subramaniam
authors.forename: George T
authors.initials: GT
authors.lastname: De Sanctis
authors.forename: Jack A
authors.initials: JA
authors.lastname: Elias
authors.forename: Jeffrey M
authors.initials: JM
authors.lastname: Drazen
authors.forename: Eric S
authors.initials: ES
authors.lastname: Silverman
mesh_terms: D000403:Airway Resistance / Q000235:genetics* / Q000502:physiology*; D000818:Animals; D001249:Asthma / Q000201:enzymology / Q000378:metabolism; D015152:Blotting, Northern; D015153:Blotting, Western; D001992:Bronchoalveolar Lavage Fluid / Q000166:cytology; D001993:Bronchodilator Agents / Q000494:pharmacology; D018076:DNA, Complementary / Q000096:biosynthesis / Q000235:genetics; D004318:Doxycycline / Q000378:metabolism; D007150:Immunohistochemistry; D008168:Lung / Q000201:enzymology* / Q000502:physiology*; D016210:Methacholine Chloride / Q000494:pharmacology; D051379:Mice; D008822:Mice, Transgenic; D009569:Nitric Oxide / Q000378:metabolism / Q000502:physiology; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors* / Q000096:biosynthesis; D052247:Nitric Oxide Synthase Type II; D015656:Respiratory Mechanics / Q000235:genetics / Q000502:physiology; D020545:Respiratory Mucosa / Q000378:metabolism / Q000502:physiology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013752:Tetracycline / Q000378:metabolism; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism; D019076:Transgenes; D014598:Uteroglobin / Q000235:genetics
chemical_list: D001993:Bronchodilator Agents; D018076:DNA, Complementary; C556390:Scgb1a1 protein, mouse; D015534:Trans-Activators; D016210:Methacholine Chloride; D009569:Nitric Oxide; D014598:Uteroglobin; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496317:Nos2 protein, mouse; D013752:Tetracycline; D004318:Doxycycline