Effects of polymyxin B and Salmonella typhimurium antiserum on horses given endotoxin intravenously.
Polymyxin B and an antiserum against an Re mutant Salmonella typhimurium were evaluated for protective effect in an equine model endotoxemia. Six 3- to 5-month-old foals were given endotoxin (0.25 micrograms/kg of body weight) IV after no pretreatment, or pretreatment with polymyxin B (6,000 U/kg, IV) or S typhimurium antiserum (1.5 ml/kg, IV). When given without pretreatment, endotoxin caused transient recumbency and increases in rectal temperature, and heart and respiratory rates. In addition, leukopenia and increases in circulating tumor necrosis factor (TNF) and interleukin 6 (IL-6) activities were detected. Compared with results obtained when endotoxin was given alone, pretreatment with polymyxin B resulted in significantly (P < 0.05) lower maximal plasma TNF and IL-6 activities, and significantly lower rectal temperature and respiratory rate. In contrast, compared with effects of endotoxin given without pretreatment, use of antiserum was associated with significantly (P < 0.05) higher respiratory rate, maximal plasma IL-6 activity, and total TNF response (as determined by areas under curves of plasma TNF vs time). These results indicate that polymyxin B may have potential as a treatment for equine endotoxemia. Salmonella typhimurium antiserum had no positive effect in this model, and, under certain conditions, may exacerbate the actions of endotoxin.
Department of Large Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville 32610.
M M
MM
Durando
R J
RJ
MacKay
S
S
Linda
L A
LA
Skelley
D000818:Animals; D001831:Body Temperature / Q000187:drug effects; D004731:Endotoxins / Q000633:toxicity*; D004926:Escherichia coli; D006339:Heart Rate / Q000187:drug effects; D006736:Horses; D007116:Immunization, Passive; D015850:Interleukin-6 / Q000097:blood; D007958:Leukocyte Count / Q000187:drug effects; D008070:Lipopolysaccharides / Q000633:toxicity*; D011112:Polymyxin B / Q000627:therapeutic use*; D012119:Respiration / Q000187:drug effects; D012486:Salmonella typhimurium / Q000276:immunology*; D014115:Toxemia / Q000097:blood / Q000276:immunology / Q000517:prevention & control*; D014409:Tumor Necrosis Factor-alpha / Q000032:analysis
D004731:Endotoxins; D015850:Interleukin-6; D008070:Lipopolysaccharides; D014409:Tumor Necrosis Factor-alpha; D011112:Polymyxin B