The release of prostanoids during the acute pulmonary response to E. coli endotoxin in anaesthetized cats

Abstract

1 The administration of E. coli endotoxin (2 mg/kg i.v.) to anaesthetized cats results in a characteristic acute pulmonary response. This consists of increases in pulmonary artery pressure and airways resistance and a reduction in lung compliance. 2 Plasma concentrations of prostaglandin E₂ (PGE₂), PGF_2α, thromboxane B₂ and 6-keto PGF_1α were measured by radioimmunoassay in aortic and pulmonary arterial blood samples before, during and after the acute pulmonary response to endotoxin. 3 Endotoxin administration resulted in the rapid release of PGF_2α and thromboxane B₂ from the lungs. The time course of this release was parallel to that of the pulmonary hypertensive and airways responses to endotoxin. PGE₂ and 6-keto PGF_1α were released more gradually and with greater variations between individual animals. 4 During the delayed shock phase (2 h after endotoxin) the concentrations of PGE₂, PGF_2α and 6-keto PGF_1α were once again elevated in both the aorta and pulmonary artery. Thromboxane B₂ concentrations were not increased at this time. 5 These results suggest that PGF_2α and thromboxane A₂ may be mediators of the acute pulmonary responses to endotoxin.