Document Detail

Role of endothelium and nitric oxide in the in vitro response of equine colonic venous rings to vasoconstrictor agents.
MedLine Citation:
PMID:  9328669     Owner:  NLM     Status:  MEDLINE    
OBJECTIVE: To determine in vitro contractile responses of equine colonic veins to various vasoconstrictor agents. ANIMALS: Colonic veins collected from 8 adult horses. PROCEDURE: Veins were cut into 4-mm-wide rings, placed in organ baths at 37 C, and attached to a force-transducer interfaced with a polygraph; 2 g of tension was applied, and rings were allowed to equilibrate for 45 minutes. Bath solution was replaced, and tension was reapplied at 15-minute intervals. Cumulative concentration responses (10(-8) to 10(-4) M) were determined for each agent, using separate rings (n = 8). Three vein groups were evaluated: endothelium-intact, endothelium-denuded, and N omega-nitro-L-arginine methyl ester (L-NAME, 10(-5) M)-treated. Maximal responses by each vein to each agent were considered 100%; responses to lower concentrations were calculated as percentage of maximum. RESULTS: Considering all vein groups, comparison of the doses that caused 50% of the maximal contraction revealed relative sensitivity of colonic veins to be: angiotensin II (ANG) > thromboxane B2 analogue (TXB) > 5-hydoxytryptamine (5HT) > norepinephrine (NE) > histamine (HST) > prostaglandin F2 alpha (PGF) > vasopressin (VP). Compared with ANG, PGF, TXB, and VP, treatment with HST, 5HT, and NE evoked significantly greater responses. Endothelium-denuded and L-NAME-treated colonic veins had significantly greater maximal contractile responses than did endothelium-intact veins. CONCLUSIONS: Response of colonic veins to vasoconstrictor agents was differential; sensitivity was not altered by endothelium removal or L-NAME treatment; maximal responses of endothelium-intact veins were greater than those of endothelium-denuded and L-NAME-treated veins; and responses of endothelium-denuded and L-NAME-treated veins were not different. CLINICAL RELEVANCE: Alterations in colonic veins that mimic conditions associated with large-colon volvulus may contribute to blood flow alterations, edema formation, and vascular responses to hypovolemic and endotoxic shock.
R M Moore; C S Venugopalan; S A Sedrish; E P Holmes
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Publication Detail:
Type:  Comparative Study; In Vitro; Journal Article; Research Support, U.S. Gov't, Non-P.H.S.    
Journal Detail:
Title:  American journal of veterinary research     Volume:  58     ISSN:  0002-9645     ISO Abbreviation:  Am. J. Vet. Res.     Publication Date:  1997 Oct 
Date Detail:
Created Date:  1997-12-31     Completed Date:  1997-12-31     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0375011     Medline TA:  Am J Vet Res     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  1145-51     Citation Subset:  IM    
Department of Veterinary Clinical Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge 70803-8410, USA.
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MeSH Terms
Analysis of Variance
Angiotensin II / pharmacology
Colon / blood supply*,  drug effects
Dinoprost / pharmacology
Dose-Response Relationship, Drug
Endothelium, Vascular / drug effects,  physiology*
Histamine / pharmacology
Horses / physiology*
NG-Nitroarginine Methyl Ester / pharmacology
Nitric Oxide / physiology*
Norepinephrine / pharmacology
Sensitivity and Specificity
Thromboxane B2 / pharmacology
Vasoconstriction / drug effects,  physiology
Vasoconstrictor Agents / pharmacology*
Vasopressins / pharmacology
Veins / drug effects,  physiology
Reg. No./Substance:
0/Vasoconstrictor Agents; 10102-43-9/Nitric Oxide; 11000-17-2/Vasopressins; 11128-99-7/Angiotensin II; 50903-99-6/NG-Nitroarginine Methyl Ester; 51-41-2/Norepinephrine; 51-45-6/Histamine; 54397-85-2/Thromboxane B2; 551-11-1/Dinoprost

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

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