Document Detail

Persistent fetal pulmonary hypoperfusion after acute hypoxia.
MedLine Citation:
PMID:  2889374     Owner:  NLM     Status:  MEDLINE    
To determine the effects of duration of hypoxia on fetal pulmonary blood flow and vasoreactivity, we studied the response of the fetal pulmonary vascular bed before, during, and after prolonged (2-h) and more brief (30-min) exposures to acute hypoxia in 19 chronically instrumented unanesthetized fetal lambs. Left pulmonary arterial blood flow was measured by an electromagnetic flow transducer. Fetal PO2 was lowered by delivering 10-12% O2 to the ewe. During 2-h periods of hypoxia left pulmonary arterial blood flow decreased, and main pulmonary arterial and pulmonary vascular resistance increased. The increase in pulmonary vascular resistance was sustained throughout the 2-h period of hypoxia. After the return of the ewe to room air breathing, pulmonary vascular resistance remained elevated for at least 1 h despite the rapid correction of hypoxemia and in the absence of acidemia. In contrast, after 30 min of hypoxia, left pulmonary arterial blood flow, pulmonary arterial pressure, and pulmonary vascular resistance returned to base-line values rapidly with the termination of hypoxia. The persistent pulmonary hypoperfusion after 2 h of hypoxia was attenuated by alpha-adrenergic blockade and was characterized by a blunted vasodilatory response to increases in fetal PO2. When fetal PO2 was elevated during the posthypoxia period in the presence of alpha-blockade, pulmonary blood flow still remained unresponsive to increases in fetal PO2. We conclude that 2-h periods of acute hypoxia can decrease fetal pulmonary vasoreactivity, and we speculate that related mechanisms may contribute to the failure of the normal adaptation of the pulmonary circulation at birth.
S H Abman; F J Accurso; R B Wilkening; G Meschia
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  The American journal of physiology     Volume:  253     ISSN:  0002-9513     ISO Abbreviation:  Am. J. Physiol.     Publication Date:  1987 Oct 
Date Detail:
Created Date:  1987-11-19     Completed Date:  1987-11-19     Revised Date:  2007-11-15    
Medline Journal Info:
Nlm Unique ID:  0370511     Medline TA:  Am J Physiol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  H941-8     Citation Subset:  IM    
Department of Pediatrics, University of Colorado School of Medicine, Denver 80262.
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MeSH Terms
Adrenergic alpha-Antagonists / pharmacology
Anoxia / physiopathology*
Lung / embryology*
Phentolamine / pharmacology
Pulmonary Circulation
Regional Blood Flow
Vascular Resistance
Grant Support
Reg. No./Substance:
0/Adrenergic alpha-Antagonists; 50-60-2/Phentolamine

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