Document Detail

Effect of long-term tilt on mechanical and electrical properties of rat saphenous vein.
MedLine Citation:
PMID:  2705557     Owner:  NLM     Status:  MEDLINE    
Femoral vein pressure in adult male Sprague-Dawley rats kept in specially designed tubelike cages rose immediately from a control value of 2.9 +/- 0.2 (SE) mmHg to a gravity-induced sustained value of 5.9 +/- 0.2 mmHg on initiation of a 2-wk 45 degrees head-up tilt period. Femoral arterial pressure was not altered by tilting. In 2 wk mean external diameter, but not total wall thickness, of in vitro distal saphenous vein segments from tilted rats was increased approximately 30% above that of segments from nontilted controls at each of four successive 5-mmHg intralumenal pressure (IP) increments applied between 0 and 20 mmHg. Consequently, in tilted rats isobaric stress was increased 38% at low and 24% at high IP, whereas incremental distensibility was decreased at mid IP. Vascular smooth muscle (VSM) in tilted rat vein, but not artery, was hyperpolarized relative to controls both in vitro at normal physiological pressures [membrane potential (Em) = -58.2 +/- 0.8 vs. -52.4 +/- 0.8 mV, respectively] and in situ during local neural blockade (Em = -61.3 +/- 2.3 vs. -53.5 +/- 0.5 mV, respectively). The conclusion is that a moderate chronic elevation of IP in a vein results in hyperpolarization of its VSM and an elevation of its total capacity due to an as yet unexplained mechanism of physiological adaptation.
E Monos; S J Contney; A W Cowley; W J Stekiel
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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:  256     ISSN:  0002-9513     ISO Abbreviation:  Am. J. Physiol.     Publication Date:  1989 Apr 
Date Detail:
Created Date:  1989-05-12     Completed Date:  1989-05-12     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:  H1185-91     Citation Subset:  IM; S    
Department of Physiology, Medical College of Wisconsin, Milwaukee 53226.
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MeSH Terms
Adaptation, Physiological
Membrane Potentials
Muscle, Smooth, Vascular / physiology*
Rats, Inbred Strains
Saphenous Vein / physiology*
Stress, Mechanical
Venous Pressure
Grant Support

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