Kinetics, dose response, tachyphylaxis and cross‐tachyphylaxis of vascular leakage induced by endotoxin, zymosan‐activated plasma and platelet‐activating factor in the horse

摘要

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 endotoxaem