Role of thromboxane A(2) and platelet activating factor in early haemodynamic response to lipopolysaccharide in rats

The mechanism of early pulmonary and systemic haemodynamic response to intr avenous infusion of LPS from Escherichia coli was investigated in anastheti sed Wistar rats. 10 mg of LPS given at a rate of 4 mg/kg/min but not at a r ate of 1 mg/kg/min induced an increase in pulmonary arterial pressure (SAP) and a fall in systemic arterial pressure (SAP). Pretreatment with a PAF re ceptor antagonist; WEB 2170 (5 and 25 mg/kg) inhibited both PAP and SAP res ponses to LPS (4 mg/kg/min) while an inhibitor of thromboxane synthesis; Ca monagrel (10 and 20 mg/kg) abolished PAP response without a major effect on SAP response to LPS. In conclusion, both PAF and TXA(2) mediate LPS induce d rise in pulmonary arterial pressure while LPS-induced fall in systemic ar terial pressure is mediated by PAF.