Changes in the levels of prostaglandins and thromboxane and their roles in the accumulation of exudate in rat carrageenin-induced pleurisy — a profile analysis using gas chromatography-mass spectrometry —

Abstract

Injection of γ-carrageenin into t he pleural cavity of rats caused the accumulation of the pleural exudate. When levels of prostaglandins (PGs) and thromboxane (TX) B 2 were quantified by gas chromatography-mass spectrometry as their methyl ester (ME)-dimethyllisopropylsilyl (DMiPS) ether or ME-methoxine-DMiPS ether derivatives, 6-keto-PGF 1α reached the maximum at 1 hr after carrageenin, then PGE 2 and TXB 2 showed peaks at 3 hr and waned off before 9 hr. he PGF 2α level was kept low, but PGD 2, PGE 1 and PGF 1α were not detected. Aspirin (100 mg/kg, i.p.) significantly decreased the PG and TXB 2 levels and suppressed the rate of plasma exudation until 5 hr, but did not at 7 hr, when it was measured by the amount of exuded pontamine sky blue injected intravenously. OKY-025 (300 mg/kg, i.p.), a selective TXA synthetase inhibitor, and tranylcypromine (20 mg/kg, i.p.), a PGI synthetase inhibitor, could not extensively inhibit the accumulation of the exudate. These results suggest that the cyclooxygenase products of arachidonic acid, particularly PGE 2, definitely play an important role in the exudation during the first 5 hr.