Document Detail

Simulated microgravity increases myogenic tone in rat cerebral arteries.
MedLine Citation:
PMID:  9804560     Owner:  NLM     Status:  MEDLINE    
Adaptation of the cerebral circulation to microgravity was investigated in rat middle cerebral arteries after 20 days of hindlimb unweighting (HU). Myogenic responses were measured in isolated, pressurized arteries from HU and control animals. Maximal passive lumen diameters, obtained in the absence of extracellular Ca2+ plus EDTA, were not significantly different between groups (249 vs. 258 micrometer). In physiological salt solution, arteries from both HU and control animals maintained a constant lumen diameter when subjected to incremental increases in transmural pressure (20-80 mmHg). However, the diameter of arteries from HU animals was significantly smaller than that of arteries from control animals at all pressures; this difference could be eliminated by exposure to the nitric oxide synthase inhibitor NG-nitro-L-arginine methyl ester. After HU treatment, transient distensibility of the artery wall in response to pressure was also significantly decreased, whereas the frequency and amplitude of vasomotion were increased. The latter changes were not affected by NG-nitro-L-arginine methyl ester. Thus simulated microgravity increases cerebral artery myogenic tone through both nitric oxide synthase-dependent and -independent mechanisms.
G G Geary; D N Krause; R E Purdy; S P Duckles
Publication Detail:
Type:  In Vitro; Journal Article; Research Support, U.S. Gov't, Non-P.H.S.; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Journal of applied physiology (Bethesda, Md. : 1985)     Volume:  85     ISSN:  8750-7587     ISO Abbreviation:  J. Appl. Physiol.     Publication Date:  1998 Nov 
Date Detail:
Created Date:  1998-12-29     Completed Date:  1998-12-29     Revised Date:  2013-09-26    
Medline Journal Info:
Nlm Unique ID:  8502536     Medline TA:  J Appl Physiol (1985)     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  1615-21     Citation Subset:  IM; S    
Department of Pharmacology, College of Medicine, University of California, Irvine, California 92697-4625, USA.
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MeSH Terms
Calcium / physiology
Cerebral Arteries / physiology*
Enzyme Inhibitors / pharmacology
Hindlimb Suspension
Muscle Contraction / physiology
Muscle Tonus / physiology
Muscle, Smooth, Vascular / physiology*
NG-Nitroarginine Methyl Ester / pharmacology
Nitric Oxide / physiology
Nitric Oxide Synthase / antagonists & inhibitors
Rats, Wistar
Weightlessness Simulation / adverse effects*
Grant Support
Reg. No./Substance:
0/Enzyme Inhibitors; 10102-43-9/Nitric Oxide; 50903-99-6/NG-Nitroarginine Methyl Ester; 7440-70-2/Calcium; EC Oxide Synthase
R E Purdy / U CA, Irvine

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