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United States Department of Agriculture

Agricultural Research Service

Title: Evaluation of the Vasoconstrictive Capacity of Tall Fescue Alkaloids Using Fescue Naive Bovine Lateral Saphenous Veins

Authors
item Klotz, James
item Kirch, Brett
item Aiken, Glen
item Bush, Lowell - UNIVERSITY OF KENTUCKY
item Arrington, Brad - UNIVERSITY OF KENTUCKY
item Strickland, James

Submitted to: Journal of Animal Science Supplement
Publication Type: Abstract Only
Publication Acceptance Date: February 14, 2006
Publication Date: July 9, 2006
Citation: Klotz, J.L., Kirch, B.H., Aiken, G.E., Bush, L.P., Arrington, B.C., Strickland, J.R. 2006. Evaluation of the Vasoconstrictive Capacity of Tall Fescue Alkaloids Using Fescue Naive Bovine Lateral Saphenous Veins. Journal of Animal Science Supplement. 84:54.

Interpretive Summary: No summary

Technical Abstract: Vasoconstriction is associated with consumption of toxic endophyte-infected tall fescue. Because it is not known if endophyte-produced alkaloids act alone or in concert, the objective of this study was to examine the vasoconstrictive potentials of D-lysergic acid (LSA) and ergovaline (ERV) individually or in combination with N-acetyl loline (NAL) using bovine lateral saphenous veins biopsied from fescue naïve cattle. Segments (2-3 cm) of vein were surgically biopsied from healthy cross-bred yearling cattle (n=5; 360 '20 kg). Veins were trimmed of excess fat and connective tissue, sliced into 2-3 mm sections and suspended in a myograph chamber containing 5 mL of oxygenated Krebs-Henseleit buffer (95% O2/5% CO2; pH = 7.4; 37'C). Tissue was allowed to equilibrate at 1 g of tension for 90 min prior to initiation of treatment additions. Increasing doses of ERV or LSA (1x10-11 to 1x10-4 M) with or with out NAL (1x10-5 M) were administered every 15 min following buffer replacement. Data were normalized as a percent of contractile response induced by a reference dose of norepinephrine (1x10-4 M). Increasing concentrations of LSA did not result in an appreciable contractile response until the addition of 1x10-4 M LSA (22.6 ' 4.1%). A vascular response to increasing concentrations of ERV was apparent at 1x10-8 M (4.7 ' 2.2%) and increased to a maximum of 104.2 ' 6.0% with the addition of 1x10-4 M ERV. The presence of NAL did not alter the onset or magnitude of vascular response to either LSA or ERV (maximum responses of 24.9 ' 4.5 and 101.5 ' 10.9%, respectively). These data indicate that ERV is a more potent vascular toxicant than lysergic acid. Further, the presence of NAL did not inhibit or potentiate the effects of the ergot alkaloids on vascular activity. If these data persist in additional physiological systems, then tall fescue forages containing LSA and/or NAL should be safer for animal consumption than those containing ERV. Bovine, Alkaloids, Saphenous Vein

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