Mf. Mulder et al., SYSTEMIC AND REGIONAL HEMODYNAMIC-CHANGES DURING ENDOTOXIN OR PLATELET-ACTIVATING-FACTOR (PAF)-INDUCED SHOCK IN RATS, Circulatory shock, 41(4), 1993, pp. 221-229
To evaluate the role of platelet activating factor (PAF) during endoto
xin shock, we compared its effects with those of endotoxin. We measure
d arterial pressure (MAP), heart rate (HR), cardiac output (CO; thermo
dilution), arterial lactate (C(a)lact), organ blood flow (radioactive
microspheres), and organ vascular resistance in four groups of anesthe
tized (pentobarbital) male Wistar rats (n = 7 per group), infused from
t = 0 to t = 60 min with saline (group C: time matched control), endo
toxin Escherichia coli O127:B8, 8 mg . kg(-1) (group E), a ''low PAF d
ose'' (1 mu g . kg(-1)) to cause the same decrease in MAP as in group
E (group PL), or a ''high PAF dose'' (3 mu g . kg(-1)) to cause the sa
me decrease in CO as in group E (group PH). At t = 60 min, MAP had dec
reased by 33% in E and PL, and by 55% in PH group. CO had decreased by
41% in the E and PH group. C(a)lact had increased in the E and PH gro
up by 300 and 200%, respectively. In the 8, PL and PH group, coronary
vascular resistance decreased. In the splanchnic organs, endotoxin cau
sed a decrease in blood flow due to vasoconstriction, whereas PAF (bot
h concentrations) caused vasodilation (except for spleen). Penal vascu
lar resistance decreased (P < 0.05) in the PL group. In all groups, va
scular resistance had increased (P < 0.05) in skin, and not changed in
skeletal muscle (P < 0.05). Thus, hemodynamic changes after PAF infus
ion were partially similar to those after endotoxin infusion (coronary
vasodilation and vasoconstriction in spleen and skin). However, in th
e splanchnic region (except the spleen) and in the kidney, PAF had a v
asodilatory effect, whereas endotoxin had not. In separate experiments
, PAF was not detectable in the blood of endotoxin-treated rats, where
as it was in the PAF-treated rats. Additionally, the PAF antagonist BN
52021 had no beneficial effect on MAP, CO, and C(a)lact in rats treate
d with endotoxin as a bolus. In conclusion, most systemic and regional
hemodynamic changes during endotoxin shock are not mediated by PAF. (
C) 1993 Wiley-Liss, Inc.