Leukotriene B4 production in normal rat glomeruli

Abstract

The production of the lipoxygenase metabolite of arachidonic acid, leukotriene B4 (LTB4) by normal rat glomeruli has been studied. Isolated glomeruli from saline-perfused rat kidneys were incubated in Kreb's buffer for 15 min at 37 degrees C. The concentrations of LTB4 and other eicosanoids in cell-free supernatants were determined by direct radioimmunoassays (RIA). Mean basal syntheses of eicosanoids were: thromboxane B2 (TXB2) 0.77 +/- 0.13, prostaglandin (PG) E2 0.40 +/- 0.05, 6-keto-PGF1 alpha 0.38 +/- 0.06 ng/mg glomerular protein (mean +/- SEM n = 8). In these assays immunoreactive LTB4 synthesis was 0.12 +/- 0.02 ng/mg. In samples incubated with BW755C, 50 micrograms/ml, an inhibitor of arachidonate metabolism via both the cyclo-oxygenase and lipoxygenase pathways, there was more than 80% inhibition of the synthesis of TXB2, PGE2 and 6-keto-PGF1 alpha. However, immunoreactive LTB4 was only reduced by 44%, suggesting the presence of other materials which cross-react in the RIA. The presence of authentic LTB4 in the supernatants was confirmed after extraction and high-pressure liquid chromatography (HPLC). This material represented 25% of the original material detected by RIA. Although the physiological role of LTB4 in the normal state is unknown, its chemotactic activity may be of great significance during glomerular inflammation.