Chinese J Physiol
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Hyperoxia may affect lung physiology in different ways. We investigated the effect of hyperoxia on the protein expression of endothelial nitric oxide synthase (eNOS) and inducible nitric oxide synthase (iNOS), nitric oxide (NO) production, and hypoxic pulmonary vasoconstriction (HPV) in rat lung. Twenty-four male rats were divided into hyperoxic and normoxic groups. ⋯ After L-NAME administration, a second hypoxic challenge restored the HPV response in the hyperoxic group. There were increased protein expression of eNOS (12.6 +/- 3.1-fold, n = 3) (X200) and iNOS (8.1 +/- 2.6-fold, n = 3) (X200) in the hyperoxia group. We conclude that hyperoxia increases the protein expression of eNOS and iNOS with a subsequent increased release of endogenous NO, which attenuates the HPV response.