Role of endogenous nitric oxide in hyperoxia-induced airway hyperreactivity in maturing rats.
J Appl Physiol (1985)
; 89(3): 1205-12, 2000 Sep.
Article
em En
| MEDLINE
| ID: mdl-10956370
ABSTRACT
We sought to define the effects of maturation and hyperoxic stress on nitric oxide (NO)-induced modulation of bronchopulmonary responses to stimulation of vagal preganglionic nerve fibers. Experiments were performed on decerebrate, paralyzed, and ventilated rat pups at 6-7 days (n = 21) and 13-15 days of age (n = 23) breathing room air and on rat pups 13-15 days of age (n = 19) after exposure to hyperoxia (>/=95% inspired O(2) fraction for 4-6 days). Total lung resistance (RL) and lung elastance (EL) were measured by body plethysmograph. Vagal stimulation and release of acetylcholine caused a frequency-dependent increase in RL and EL in all animals. The RL response was significantly potentiated in normoxic animals by prior blockade of nitric oxide synthase (NOS) (P < 0.05). Hyperoxic exposure increased responses of RL to vagal stimulation (P < 0.05); however, after hyperoxic exposure, the potentiation of contractile responses by NOS blockade was abolished. The response of EL was potentiated by NOS blockade in the 13- to 15-day-old animals after both normoxic and hyperoxic exposure (P < 0.01). Morphometry revealed no effect of hyperoxic exposure on airway smooth muscle thickness. We conclude that NO released by stimulation of vagal preganglionic fibers modulates bronchopulmonary contractile responses to endogenously released acetylcholine in rat pups. Loss of this modulatory effect of NO could contribute to airway hyperreactivity after prolonged hyperoxic exposure, as may occur in bronchopulmonary dysplasia.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Envelhecimento
/
Hiper-Reatividade Brônquica
/
Hiperóxia
/
Óxido Nítrico
Tipo de estudo:
Etiology_studies
Limite:
Animals
Idioma:
En
Revista:
J Appl Physiol (1985)
Assunto da revista:
FISIOLOGIA
Ano de publicação:
2000
Tipo de documento:
Article
País de afiliação:
Estados Unidos