Plasma concentrations of endotoxin following jugular or portal injections of endotoxin and following gastrointestinal ischemia due to hemorrhage.

Endotoxin (LPS) was quantitated in canine plasma using the Limulus amebocyte lysate (LAL) chromogenic testing procedure. The assay was validated for sensitivity (25 pg/ml), recovery (90-110%), intra-assay precision (CV = 5.5), interassay precision (CV = 10), and stability of diluted, heat-treated, frozen samples (greater than or equal to 60 days). Canine plasma samples were analyzed for endotoxin following sublethal IV injections (cephalic and portal, bolus and slow infusion) of LPS. Pharmacokinetic analysis using the two-compartment open model on plasma LPS levels was possible for portal bolus, cephalic bolus, and portal slow infusion dogs. The results revealed that LPS given via cephalic bolus route had a lower clearance rate than LPS given via portal bolus route. Slow infusion of LPS into the portal vein revealed an increased distribution phase t1/2 in plasma and a slower elimination kel and beta rate than observed following a portal bolus injection of LPS. During a clinical endo(to)xemia, LPS enters the circulation slowly, and is therefore probably cleared more slowly; the prolonged low level of LPS may be responsible for many pathophysiological changes observed. Low levels of endotoxin were detected in plasma following hemorrhage, indicating that intestinal ischemia results in low levels of LPS leaking into the circulation.