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United States Department of Agriculture

Agricultural Research Service

Research Project: OPTIMIZING THE BIOLOGY OF THE ANIMAL-PLANT INTERFACE FOR IMPROVED SUSTAINABILITY OF FORAGE-BASED ANIMAL ENTERPRISES

Location: Forage-Animal Production Research

Title: A vascular contractility bioassay using bovine right ruminal artery and vein

Authors
item KLOTZ, JAMES
item Bush, Lowell -
item STRICKLAND, JAMES

Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 6, 2010
Publication Date: June 1, 2011
Citation: Klotz, J.L., Bush, L.P., Strickland, J.R. 2011. A vascular contractility bioassay using bovine right ruminal artery and vein. Journal of Animal Science. 89:1944-1951.

Interpretive Summary: Endophyte-infected (Neotyphodium coenophialum) tall fescue (Lolium arundinaceum) produces toxins (ergot alkaloids) that are associated with vasoconstriction of blood vessels in the extremities in grazing animals. Consumption of these alkaloids may affect blood vessels associated with digestive organs. Experiments were conducted, using dose-responses to norepinephrine and serotonin that were normalized to either 0.12 M KCl, or 0.1 mM norepinephrine or serotonin, to compare the responses of vessels equilibrated at different tensions on the day of collection or the day after collection. the right ruminal artery and vein bioassay is best run using 0.12 M KCl as a reference compound to normalize experimental data. The ruminal artery responded best when adjusted to a resting tension of 1.0 g, whereas the ruminal vein produced better results when equilibrated at resting tension of 0.5 g. Both types of ruminal vessel responded well the day after collection. Development of this bioassay allows the separation of the effects tall fescue alkaloids exert on both the right ruminal artery and vein as representative vessels that service digestive tissues in grazing animals.

Technical Abstract: Endophyte-infected (Neotyphodium coenophialum) tall fescue (Lolium arundinaceum) produces ergot alkaloids that are associated with peripheral vasoconstriction in grazing animals and ingestion of these alkaloids may affect splanchnic vasculature. Because of significant differences in morphological and functional characteristics between vasculature supporting digestive and peripheral tissues, the bovine foregut vascular model required validation. Experiments were conducted, using dose-responses to norepinephrine and serotonin that were normalized to either 0.12 M KCl, or 0.1 mM norepinephrine or serotonin, to compare the responses of vessels equilibrated at different tensions on the day of collection or the day after collection. Segments of a branch of right ruminal artery and vein were collected from the ventral coronary groove of healthy mixed breed, age, and gender cattle (n = 20) at local abattoirs. Cross-sections of artery and vein were suspended on luminal supports in a chamber of a multi-myograph containing continuously oxygenated Krebs-Henseleit buffer (95% O2/5% CO2; pH=7.4; 37°C). Vessels were allowed to equilibrate at either 0.5 or 1.0 g of tension for 1.5 h prior to exposure to a reference compound. Increasing concentrations of each biogenic amine were administered in 15-min intervals following buffer replacement. Data were normalized as a percent of contractile response induced by reference compound for each tension and day of analysis. Ruminal artery and vein were both more responsive to KCl as a reference compound (P < 0.05) than norepinephrine or serotonin and did not differ between days when normalized with KCl. Ruminal arteries had greater contractile response when tension was set to 1.0 g during equilibration compared to 0.5 g (P < 0.05). Ruminal vein response had a more stable maintenance of baseline tension in vessels equilibrated at 0.5 g of resting tension. Development of this bioassay allows the separation of the effects tall fescue alkaloids exert on both the right ruminal artery and vein as representative vessels that service tissues functioning in nutrient absorption.

Last Modified: 9/29/2014
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