title: Contribution of nitric oxide to adaptation of tibetan sheep to high altitude.
abstract: We examined the effects of endogenous nitric oxide synthase (NOS) inhibition on pulmonary hemodynamics in awake sheep living at low and high altitudes to evaluate the role of NO in adaptation to an hypoxic environment. Unanaesthetized male sheep in three places--Matsumoto, Japan (680 m above sea level), Xing, China (2300 m) and Maxin, China (3750 m)--were prepared for measurements of pulmonary artery (Ppa) and pulmonary vascular resistance (PVR) before and after the NOS inhibition. The non-selective NOS inhibitor, Nw-nitro-l-argine (NLA, 20 mg/kg) was used. Baseline Ppa became elevated with an increase in altitude. After NLA administration, PVR significantly increased in animals of all groups. However, the increase in PVR after NLA in tibetan sheep at 3750 m was significantly higher than those in other groups. We conclude that augmented endogenous NO production may contribute to regulating the pulmonary vascular tone in tibetan sheep (3750 m) adapted to high altitude.
authors.affiliation: First Department of Medicine, Shinshu University School of Medicine, 3-1-1 Asahi, Matsumoto 390-8621, Japan. tomonobu@hsp.md.shinshu-u.ac.jp
authors.forename: Tomonobu
authors.initials: T
authors.lastname: Koizumi
authors.forename: Zonghai
authors.initials: Z
authors.lastname: Ruan
authors.forename: Akio
authors.initials: A
authors.lastname: Sakai
authors.forename: Takeshi
authors.initials: T
authors.lastname: Ishizaki
authors.forename: Takaaki
authors.initials: T
authors.lastname: Matsumoto
authors.forename: Muneo
authors.initials: M
authors.lastname: Saitou
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Matsuzaki
authors.forename: Keishi
authors.initials: K
authors.lastname: Kubo
authors.forename: Zhangang
authors.initials: Z
authors.lastname: Wang
authors.forename: Qiuhong
authors.initials: Q
authors.lastname: Chen
authors.forename: Xiaoqin
authors.initials: X
authors.lastname: Wang
mesh_terms: D000222:Adaptation, Physiological / Q000502:physiology*; D000531:Altitude; D000578:Amidines / Q000494:pharmacology; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006439:Hemodynamics / Q000187:drug effects; D006574:Heterocyclic Compounds, 2-Ring / Q000494:pharmacology; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009569:Nitric Oxide / Q000502:physiology*; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors / Q000378:metabolism; D011651:Pulmonary Artery / Q000187:drug effects / Q000502:physiology; D012756:Sheep / Q000502:physiology*; D018609:Tibet; D014655:Vascular Resistance / Q000187:drug effects / Q000502:physiology; D014851:Wakefulness / Q000502:physiology
chemical_list: C407360:7-chloro-3-imino-5-methyl-2-azabicyclo(4.1.0)heptane; D000578:Amidines; D004791:Enzyme Inhibitors; D006574:Heterocyclic Compounds, 2-Ring; D009569:Nitric Oxide; D019001:Nitric Oxide Synthase; D019331:NG-Nitroarginine Methyl Ester