Kinetics, dose response, tachyphylaxis and cross-tachyphylaxis of vascular leakage induced by endotoxin, zymosan-activated plasma and platelet-activating factor in the horse.
Vascular leakage induced by intradermal injection of endotoxin, zymosan-activated plasma (ZAP) and platelet-activating factor (PAF) was measured in nine Thoroughbreds using 125-iodine human serum albumin (125I-HSA) as a marker in the blood. ZAP and PAF produced dose-dependent increases in vascular permeability with the maximum occurring within the first 15 min after injection. The vascular leakage induced by endotoxin was also dose-dependent, but the maximum occurred 2 h after intradermal injection. Intradermal sites previously injected with endotoxin were refractory to a second injection of endotoxin for up to 5 days. However, sites injected with endotoxin and re-injected with either ZAP or PAF remained responsive with increased vascular leakage compared to saline injected control sites re-injected with either ZAP or PAF. Diminished response to endotoxin challenge may contribute to the poor prognosis of endotoxaemia in the horse.
Mills
P C
PC
Department of Veterinary Pathology, University of Queensland, St. Lucia, Australia.
Ng
J C
JC
Seawright
A A
AA
Auer
D E
DE
D000818:Animals; D002199:Capillary Permeability / Q000187:drug effects*; D002465:Cell Movement / Q000187:drug effects; D015936:Complement C5a / Q000494:pharmacology; D003877:Dermatitis, Contact / Q000378:metabolism / Q000662:veterinary; D004305:Dose-Response Relationship, Drug; D004730:Endothelium, Vascular / Q000187:drug effects; D004731:Endotoxins / Q000494:pharmacology*; D004926:Escherichia coli; D005260:Female; D006734:Horse Diseases / Q000378:metabolism; D006736:Horses; D007457:Iodine Radioisotopes; D007700:Kinetics; D008297:Male; D010972:Platelet Activating Factor / Q000494:pharmacology*; D012709:Serum Albumin; D013618:Tachyphylaxis; D015054:Zymosan / Q000097:blood*
D004731:Endotoxins; D007457:Iodine Radioisotopes; D010972:Platelet Activating Factor; D012709:Serum Albumin; D015936:Complement C5a; D015054:Zymosan