Contribution of nitric oxide to adaptation of tibetan sheep to high altitude.
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.
Koizumi
Tomonobu
T
First Department of Medicine, Shinshu University School of Medicine, 3-1-1 Asahi, Matsumoto 390-8621, Japan. tomonobu@hsp.md.shinshu-u.ac.jp
Ruan
Zonghai
Z
Sakai
Akio
A
Ishizaki
Takeshi
T
Matsumoto
Takaaki
T
Saitou
Muneo
M
Matsuzaki
Tetsuya
T
Kubo
Keishi
K
Wang
Zhangang
Z
Chen
Qiuhong
Q
Wang
Xiaoqin
X
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
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