Background: Endotoxic shock is associated with release of catecholamines as
well as decreased mesenteric vascular perfusion, which is thought to cause
remote organ injury, Adrenaline tolerance; was reported to decrease mortal
ity in endotoxic shock and have cross-tolerance with endotoxin tolerance, O
ur aim was to investigate the effect of these two tolerance conditions on t
he lipopolysaccharide (LPS)-induced decrease in mesenteric blood flow (MBF)
,
Methods: Adrenaline tolerance was developed by injecting 0.03 mg/kg adrenal
ine to Swiss-albino mice, gradually increasing the dose to 2 mg/kg over 5 d
ays. Endotoxin tolerance was developed by injecting saline for 4 days and L
PS 1 mg/kg at the fifth day. Control animals were injected with saline for
5 days, At 72 h after completion of injections, half of the animals in each
group were challenged with saline and the other half with 20 mg/kg LPS, at
0 h. Mesenteric blood flow was measured at 4 and 24 h.
Results: Neither endotoxin nor adrenaline tolerance prevented an LPS-induce
d decrease in MBF.
Conclusion: A low dose of LPS prior to a higher dose does riot prevent an L
PS-induced decrease in MBF and may actually prime for a decrease. Also, cat
echolamines are not primary mediators of LPS-induced decreases in MBF.