Formation of prostanoids during intravascular complement activation in the rabbit

1 Plasma concentrations of 6‐oxo‐prostaglandin F1α (6‐oxo‐PGF1α) and thromboxane B2 (TXB2) were measured by radioimmunoassay in arterial blood before and after injections of the complement activator, cobra venom factor (CVF). 2 During the control period, the concentration of 6‐oxo‐PGF1α, which gives the sum of prostacyclin plus 6‐oxo‐PGF1α, and TXB2 were, respectively, less than 20 pg ml−1 and 70 ± 15 pg ml−1. 3 Intravenous injections of CVF induced dose‐dependent, reversible elevations in the plasma levels of both prostanoids. 4 The time courses for the increases of 6‐oxo‐PGF1α and TXB2 paralleled the arterial hypotension and thrombocytopenia, suggesting the existence of a causal relationship between these parameters. 5 The results further support our hypothesis that complement‐dependent formation of arachidonic acid metabolites contributes to some of the haemodynamic and haematological changes occurring during endotoxin shock.