Chronic hypoxia-induced spontaneous and rhythmic contractions in the rat main pulmonary artery
Laboratoire de Physiologie Cellulaire Respiratoire, Institut National de la Santé et de la Recherche Médicale (Equipe Mixte 9937), and Institut Fédératif de Recherche 4, Université Bordeaux 2, 33076 Bordeaux, France The effect of chronic hypoxia (CH; 1-4 wk) on the electromechanical properties of th...
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Published in | American journal of physiology. Lung cellular and molecular physiology Vol. 281; no. 1; pp. 183 - L192 |
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Main Authors | , , , , |
Format | Journal Article |
Language | English |
Published |
United States
01.07.2001
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Subjects | |
Online Access | Get full text |
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Summary: | Laboratoire de Physiologie Cellulaire Respiratoire, Institut
National de la Santé et de la Recherche Médicale
(Equipe Mixte 9937), and Institut Fédératif de Recherche
4, Université Bordeaux 2, 33076 Bordeaux, France
The effect of chronic hypoxia
(CH; 1-4 wk) on the electromechanical properties of the rat main
pulmonary artery (MPA) was investigated. MPA rings obtained from rats
exposed for 14 days to hypobaric (50.5 kPa) CH exhibited spontaneous
and rhythmic contractions (SRCs) that were never observed in control
(normoxic) rats. SRCs were unaffected by tetrodotoxin, phentolamine,
BQ-123 and BQ-788, N -nitro- L -arginine methyl
ester, or endothelium removal. CH depolarized smooth muscle cells from
58.8 ± 9 to 38.6 ± 5.4 mV and increased the resting
cytosolic Ca 2+ concentration from 67.3 ± 11.9 to
112.5 ± 16.4 nM. CH also induced spontaneous spikelike
depolarizations. All of these effects were inhibited by external
Ca 2+ removal or nifedipine (1 µM). Moreover, depletion of
intracellular Ca 2+ stores with ryanodine (1-5 µM) or
cyclopiazonic acid (3 µM) progressively attenuated SRCs. This study
demonstrates that CH switches the MPA from a quiescent to a
spontaneously active mechanical state. Finally, the fact that SRCs
precede the development of right ventricle hypertrophy and disappear
when this hypertrophy reaches a maximal value (after 3-4 wk of CH)
suggests that SRCs may play a role in the adaptive process of the
pulmonary circulation to CH.
calcium signaling; hypobaric hypoxia; pulmonary hypertension; smooth muscle; right ventricle hypertrophy |
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Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
ISSN: | 1040-0605 1522-1504 |
DOI: | 10.1152/ajplung.2001.281.1.l183 |