Endotoxemia in dairy cattle: role of eicosanoids in reticulorumen stasis.
The role of arachidonic acid metabolites in the forestomach stasis induced by Escherichia coli endotoxin was evaluated. Six adult Holstein cows received saline solution; endotoxin at 1, 10, and 100 ng/kg of body weight; flunixin meglumine at 1.1 mg/kg of body weight; and flunixin meglumine at 1.1 mg/kg plus endotoxin at 100 ng/kg. The frequency of reticulorumen contractions, mental attitude, body temperature, respiratory rate, heart rate, and plasma concentration of prostaglandin E2, prostacyclin, and thromboxane were evaluated. Administration of saline solution and endotoxin at 1 ng/kg had no significant effects. Administration of endotoxin at 10 ng/kg did not cause significant clinical effects or alter reticulorumen contractions but enhanced synthesis of thromboxane. Administration of endotoxin at 100 ng/kg caused mild clinical signs of stasis, reduced the frequency of reticulorumen contractions, and enhanced synthesis of thromboxane and prostacyclin. Reticulorumen stasis was not accompanied by an increase in the plasma concentration of prostaglandin E2. Flunixin meglumine abolished endotoxin-induced reticulorumen stasis, tachycardia, and synthesis of arachidonic acid metabolites. Reticulorumen stasis during bovine endotoxemia is caused either by enhanced synthesis of an arachidonic acid metabolite other than prostaglandin E2 or by local synthesis of prostaglandin E2.
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Department of Large Animal Medicine, College of Veterinary Medicine, University of Georgia, Athens 30602.
D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000494:pharmacology*; D016718:Arachidonic Acid / Q000378:metabolism; D002417:Cattle; D002418:Cattle Diseases / Q000139:chemically induced / Q000378:metabolism*; D003002:Clonixin / Q000031:analogs & derivatives* / Q000494:pharmacology; D015232:Dinoprostone / Q000097:blood; D004731:Endotoxins / Q000037:antagonists & inhibitors* / Q000633:toxicity; D004926:Escherichia coli; D005260:Female; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects; D011460:Prostaglandins F / Q000097:blood; D012159:Reticulum / Q000187:drug effects*; D012417:Rumen / Q000187:drug effects*; D013272:Stomach Diseases / Q000378:metabolism / Q000662:veterinary*; D013929:Thromboxane B2 / Q000097:blood
D000894:Anti-Inflammatory Agents, Non-Steroidal; D004731:Endotoxins; D011460:Prostaglandins F; D016718:Arachidonic Acid; D013929:Thromboxane B2; C014558:flunixin meglumine; D015232:Dinoprostone; D003002:Clonixin; C100006:prostaglandin F1