The effects of slow infusion of a low dosage of endotoxin in healthy horses.
The effects of slow intravenous (i.v.) infusion of a very low dosage of endotoxin (a cumulative dosage of 0.03 microgram/kg bodyweight [bwt] infused over 60 mins) were evaluated in six conscious healthy horses. Duodenal, right ventral colon, and caecal contractions were detected with strain gauge force transducers. Lateral caecal arterial blood flow was measured using transit time ultrasonic blood flow probes. Duodenal contractile activity was not significantly altered by infusion of endotoxin. In contrast, the contractile activity of the right ventral colon 90 and 270 mins after infusion of endotoxin was less than after infusion of saline solution (control). The contractile activity of the caecal body 30, 60, 90, 120 and 240 mins after infusion of endotoxin was significantly less than control. The contractile activity of the caecal apex 60, 90, 120, 240 and 270 mins after termination of endotoxin infusion was significantly less than control. Lateral caecal arterial blood flow was significantly less than control at the end of endotoxin infusion and at 30, 45, 60, 90, 105 and 120 mins afterwards. Average carotid arterial pressure was significantly greater than control at 210, 225, 240, 255 and 270 mins after endotoxin infusion. Infusion of endotoxin increased heart rate, respiratory rate and body temperature significantly. The decrease in caecal contractile activity occurred before the increase in body temperature. All horses became depressed and developed injected mucous membranes. Signs of abdominal pain (including stretching, pawing, kicking at abdomen) were seen in four of the six horses.
Clark
E S
ES
Department of Large Animal Medicine, College of Veterinary Medicine, University of Georgia, Athens 30602, USA.
Moore
J N
JN
D015746:Abdominal Pain / Q000139:chemically induced / Q000503:physiopathology / Q000662:veterinary; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology; D001831:Body Temperature / Q000187:drug effects / Q000502:physiology; D002432:Cecum / Q000098:blood supply* / Q000187:drug effects / Q000502:physiology; D003106:Colon / Q000098:blood supply* / Q000187:drug effects / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D004386:Duodenum / Q000098:blood supply* / Q000187:drug effects / Q000502:physiology; D004731:Endotoxins / Q000008:administration & dosage / Q000009:adverse effects / Q000494:pharmacology*; D005260:Female; D005769:Gastrointestinal Motility / Q000187:drug effects* / Q000502:physiology; D006339:Heart Rate / Q000187:drug effects / Q000502:physiology; D006734:Horse Diseases / Q000209:etiology / Q000503:physiopathology; D006736:Horses / Q000502:physiology*; D007262:Infusions, Intravenous / Q000662:veterinary; D008297:Male; D012039:Regional Blood Flow / Q000187:drug effects; D012119:Respiration / Q000187:drug effects / Q000502:physiology; D013997:Time Factors
D004731:Endotoxins