Document Detail

Assessment of vasoconstrictive potential of D-lysergic acid using an isolated bovine lateral saphenous vein bioassay.
MedLine Citation:
PMID:  17032812     Owner:  NLM     Status:  MEDLINE    
Vasoconstriction has been associated with several symptoms of fescue toxicosis thought to be alkaloid induced. Lysergic acid, an ergot alkaloid, has been proposed as a toxic component of endophyte-infected tall fescue. The objective of this study was to examine the vasoconstrictive potential of D-lysergic acid using a bovine lateral (cranial branch) saphenous vein bioassay. Before testing lysergic acid, validation of the bovine lateral saphenous vein bioassay for use with a multimyograph apparatus was conducted using a dose-response to norepinephrine to evaluate the effects of limb of origin (right vs. left) and overnight storage on vessel contractile response. Segments (2 to 3 cm) of the cranial branch of the lateral saphenous vein were collected from healthy mixed breed cattle (n = 12 and n = 7 for the lysergic acid and norepinephrine experiments, respectively) at local abattoirs. Tissue was placed in modified Krebs-Henseleit, oxygenated buffer and kept on ice or stored at 2 to 8 degrees C until used. Veins were trimmed of excess fat and connective tissue, sliced into 2- to 3-mm sections, and suspended in a myograph chamber containing 5 mL of oxygenated Krebs-Henseleit buffer (95% O2, 5% CO2; pH = 7.4; 37 degrees C). Tissue was allowed to equilibrate at 1 g of tension for 90 min before initiation of treatment additions. Increasing doses of norepinephrine (1 x 10(-8) to 5 x 10(-4) M) or lysergic acid (1 x 10(-11) to 1 x 10(-4) M) were administered every 15 min after buffer replacement. Data were normalized as a percentage of the contractile response induced by a reference dose of norepinephrine. Veins from both left and right limbs demonstrated contractions in a dose-dependent manner (P < 0.01) but did not differ between limbs. There were no differences in dose-response to norepinephrine between tissue tested the day of dissection and tissue tested 24 h later. Exposure of vein segments to increasing concentrations of lysergic acid did not result in an appreciable contractile response until the addition of 1 x 10(-4) M lysergic acid (15.6 +/- 2.3% of the 1 x 10(-4) M norepinephrine response). These data indicate that only highly elevated concentrations of lysergic acid result in vasoconstriction. Thus, in relation to the symptoms associated with vasoconstriction, lysergic acid may only play a minor role in the manifestation of fescue toxicosis.
J L Klotz; L P Bush; D L Smith; W D Shafer; L L Smith; A C Vevoda; A M Craig; B C Arrington; J R Strickland
Publication Detail:
Type:  In Vitro; Journal Article    
Journal Detail:
Title:  Journal of animal science     Volume:  84     ISSN:  1525-3163     ISO Abbreviation:  J. Anim. Sci.     Publication Date:  2006 Nov 
Date Detail:
Created Date:  2006-10-11     Completed Date:  2006-12-18     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  8003002     Medline TA:  J Anim Sci     Country:  United States    
Other Details:
Languages:  eng     Pagination:  3167-75     Citation Subset:  IM    
Forage-Animal Production Research Unit, USDA-ARS, Lexington, KY 40546, USA.
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MeSH Terms
Biological Assay / methods,  veterinary
Dose-Response Relationship, Drug
Lysergic Acid / chemistry,  pharmacology*
Molecular Structure
Norepinephrine / administration & dosage,  pharmacology
Reproducibility of Results
Saphenous Vein / drug effects*
Vasoconstriction / drug effects*
Vasoconstrictor Agents / pharmacology*
Reg. No./Substance:
0/Vasoconstrictor Agents; 51-41-2/Norepinephrine; 82-58-6/Lysergic Acid

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

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