The detection of leukotrienes in the carrageenin-induced pleurisy of rat.

Abstract

As an inflammatory model, rat carrageenin-induced pleurisy was used. The pleural exudate was collected 5 hr after the injection of the 2% λ-carrageenin solution to the right pleural cavity. After measurement of the exudate volume, the extraction of leukotriene (LT) and HETE was performed by addition of 4-fold volumes of ethanol. This crude extract caused the very slow contraction of the guinea-pig (GP) ileum, which was similar to that of LTC4 and was inhibited by FPL55712(1 μg/ml). For further puriflication, LTC4 and LTD4 in the sample were separated as 80% ethanol eluate with Sepahdex LH-20 and LTB4, and HETEs were extracted with diethylether. After evaporation, the purified samples dissolved in methanol were applied to high perfomance liquid chromatography. The peaks, coinciding to the retention time of LTC4 and LTD4, respectively, were collected for examination of the contraction on GP ileum. The contraction by the sample was also inhibited by FPL55712. When the ratios of the contractile activity over the peak height on HPLC were compared, the values of the two peaks of the sample were similar to those of LTC4 and LTD4, respectively. LTB4 in the pleural fluid at 5 hr was smaller than 5,12-diHETE. Several mono-HETEs were also found. These results show the presence of LTC4 and LTD4 in the pleural fluid at 5 hr. As LTC4 and LTD4 are potent in plasma exudation, they might play a role in the carrageenin-induced pleurisy at 5 hr.