Measurement of prostaglandin E2 in an inflammatory exudate: effects of nonsteroidal anti-inflammatory agents.

A method was developed for extracting and measuring nanogram quantities of prostaglandin E2 (PGE2) from carrageenan-induced abscess in the rat. PGE2 concentration, quantitated by radioimmunoassay, was 42.5 and 92.9 ng/g of abscess in two studies. Anti-inflammatory activity, based on reduction in abscess weight, was observed with indomethacin, phenylbutazone, SC-19220 and A-22981; however, only indomethacin (10 mg/kg i.p.) significantly reduced PGE2 levels in the abscess tissue. Dose-related anti-inflammatory activity of indomethacin (1-10 mg/kg i.p.) was directly correlated with reductions of PGE2 content in the abscess. These data support the theory that the anti-inflammatory activity of indomethacin in the carrageenan abscess model involves inhibition of prostaglandin formation. Dose-related suppression of abscess formation by SC-19220 (7.5-30 mg/kg i.p.) was not related to changes in PGE2 levels at the inflammatory site, which suggests that the anti-inflammatory mechanism of SC-19220 is not mediated via inhibition of prostaglandin synthesis.