RELEASE OF THE LIPID PEROXIDATION MARKER 8-EPI-PROSTAGLANDIN F2α FROM ISOLATED GILL PAVEMENT CELLS

Abstract

The aim of the present study was to evaluate oxidative injury in gill pavement cells (GPCs) from fathead minnow (Pimephales promelas) using F2-isoprostane (F2-iP) release as an index of lipid peroxidation. Cells were isolated from pooled gill tissue by collagenase treatment, mechanical sieving, and Percoll density gradient centrifugation. Baseline levels of 8-epi-prostaglandin F2 alpha (8-epi-PGF2 alpha) were measured by incubating GPCs in physiological buffer (10(6) cells/ml) and enzyme immunoassay. After 60 min, the amount of immunoreactive 8-epi-PGF2 alpha (ir8-epi-PGF2 alpha) in control medium ranged from 1,374 to 5,515 pg/ml. Lead nitrate, 0.6 to 120 microM, did not influence ir8-epi-PGF2 alpha release, whereas FeCl3 stimulated release at 500 microM but not at 5 microM. Incubation medium was extracted for acidic lipids and analyzed by liquid chromatography/mass spectrometry/electrospray ionization. A compound in the medium exhibited a retention time on reverse-phase high-performance liquid chromatography nearly identical to that of synthetic 8-epi-PGF2 alpha The mass spectrum taken from the total ion chromatogram from 14.8 to 15.1 min contained a prominent ion at m/z 353, as expected for the molecular ion of 8-epi-PGF2 alpha. Similar results were obtained with tissue subjected to base hydrolysis. Mass spectra of extracted ion chromatograms obtained with gill extracts and authentic standard showed a close correspondence of fragment ions, providing definitive evidence for production and storage of F2-iPs by fish gills. In summary, F2-iP release occurs during lipid peroxidation injury to fish gill epithelium, and its measurement may facilitate aquatic toxicology studies of metallic and nonmetallic contaminants.