Document Detail


Pulmonary, vascular responses in rats exposed to chronic hypobaric hypoxia at two different altitude levels.
MedLine Citation:
PMID:  8958556     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
High altitude hypoxia is known to cause pulmonary hypertension in humans. Altitudes of 5500 m and 4000 m above sea level are considered to be the upper limits for short-term human survival and long-term human residence, respectively. To study the effects of hypobaric-hypoxic environments on pulmonary vascular beds, the physiologic and morphometric differences occurring in the pulmonary arteries of rats at the equivalent of these two altitude levels were compared. One hundred and ninety male rats were housed in a double-roomed mechanical chamber and subjected for 12 weeks to hypobaric-hypoxic environments equivalent to an altitude level of 5500 m or 4000 m. After 6-8 weeks, mean pulmonary arterial pressure (PAPm) was significantly higher in rats at the 5500 m level than in those at 4000 m. The external diameter of muscular arteries (M) and of partially muscular arteries (PM) in the lungs of rats at 8 and 12 weeks, and those of nonmuscular arteries (NM) around the alveolar sacs at 2 and 8 weeks were each significantly less in rats exposed to the 5500 m level than in those at 4000 m. At 4 weeks, the ratio of medial thickness to external diameter for M and PM around the alveolar ducts and alveolar sacs were greater in rats exposed to the 5500 m level than in those at 4000 m. Erythrocyte count, hemoglobin and hematocrit tests showed polycythemic patterns during the initial hypobaric period in both 5500 m-, and 4000 m-level rats. However, from 4 to 12 weeks, the hematologic values of the 4000 m-level rats declined progressively toward the upper end of the normal range. This study suggests (i) that elevated PAPm in rats exposed to hypobaric-hypoxic environments results from structural remodeling of all M, PM and NM within the lobule, and (ii) that an environment equivalent to the 5500 m level causes more severe pulmonary vascular changes than one equivalent to the 4000 m level. The hematologic results suggest that rats exposed to the equivalent of the upper limit for long-term human residence can acquire acclimatization, but not those exposed to the equivalent of the upper limit for short-term human survival.
Authors:
K Nakanishi; F Tajima; H Osada; A Nakamura; S Yagura; T Kawai; M Suzuki; C Torikata
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Pathology, research and practice     Volume:  192     ISSN:  0344-0338     ISO Abbreviation:  Pathol. Res. Pract.     Publication Date:  1996 Oct 
Date Detail:
Created Date:  1997-03-07     Completed Date:  1997-03-07     Revised Date:  2003-11-14    
Medline Journal Info:
Nlm Unique ID:  7806109     Medline TA:  Pathol Res Pract     Country:  GERMANY    
Other Details:
Languages:  eng     Pagination:  1057-67     Citation Subset:  IM; S    
Affiliation:
Biochemical Division, Japan Air Self-Defense Force, Tachikawa, Japan.
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MeSH Terms
Descriptor/Qualifier:
Altitude Sickness / etiology,  physiopathology*
Animals
Anoxia / pathology*,  physiopathology*
Atmospheric Pressure*
Hypertension, Pulmonary / etiology
Lung / blood supply*,  pathology*
Male
Pulmonary Artery / pathology
Rats
Rats, Wistar
Respiratory Function Tests

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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