Document Detail

Cerebrovascular reactivity to adenosine analogues in 0.6-0.7 gestation and near-term fetal sheep.
MedLine Citation:
PMID:  1590435     Owner:  NLM     Status:  MEDLINE    
During acute hypoxia, fetal sheep less than 0.7 gestation increase cerebral blood flow (CBF) relatively less than fetal sheep near term. We hypothesized that cerebrovascular reactivity to a hypoxic vasodilator metabolite such as adenosine might be diminished in immature fetuses. This study examined cerebral vasoreactivity to adenosine analogues in nine sheep fetuses less than 0.7 gestation (90-103 days) and nine near term (129-143 days). Fetuses were equipped in utero with a closed cranial window, and pial arterioles were studied by intravital microscopy. 5'-(N-ethylcarboxamido)-adenosine (NECA; 10(-9)-10(-5) M) and N6-cyclopentyladenosine (CPA; 10(-9)-10(-4) M) each caused a dose-dependent increase in arteriolar diameter that was attenuated in the presence of the adenosine receptor antagonist 8-phenyltheophylline (8-PT; 5 x 10(-6) M). Dose-response curves to the agonists were similar for both age groups. NECA was a more potent vasodilator than CPA, in keeping with their affinity for the A2 receptor. Suffusion of 8-PT alone at less than 10(-5) M had no effect on arteriolar diameter. We conclude that adenosine is able to dilate fetal cerebral arterioles as young as 0.6 gestation by acting at an A2 receptor, although resting tone is not influenced by adenosine. The immature fetal sheep CBF response to hypoxia is not attributable to undeveloped vasoreactivity to adenosine.
C D Kurth; L C Wagerle
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  The American journal of physiology     Volume:  262     ISSN:  0002-9513     ISO Abbreviation:  Am. J. Physiol.     Publication Date:  1992 May 
Date Detail:
Created Date:  1992-06-24     Completed Date:  1992-06-24     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  0370511     Medline TA:  Am J Physiol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  H1338-42     Citation Subset:  IM    
Department of Anesthesiology, Children's Hospital of Philadelphia, Pennsylvania.
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MeSH Terms
Adenosine / analogs & derivatives*,  pharmacology
Arterioles / drug effects
Cerebrovascular Circulation / drug effects*
Fetus / physiology*
Gestational Age
Theophylline / analogs & derivatives,  pharmacology
Vasodilator Agents / pharmacology
Grant Support
Reg. No./Substance:
0/Vasodilator Agents; 35920-39-9/Adenosine-5'-(N-ethylcarboxamide); 41552-82-3/N(6)-cyclopentyladenosine; 58-55-9/Theophylline; 58-61-7/Adenosine; 961-45-5/8-phenyltheophylline

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

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