Stimulation of prostaglandin synthesis in cultured liver cells by CCl4

The contribution of hepatocytes to liver prostaglandin synthesis is controversial, partly because hepatocytes of varying purity have been studied, In this study, prostaglandin synthesis was examined in conventional and ricin-purified rat hepatocytes that were incubated with gaseous carbon tetrachloride as a model stimulus for Lipid peroxidation and prostaglandin synthesis. Hepatocytes that were incubated for 2 hours with 1 mt of liquid CCl4/5 L gas volume showed no evidence of cell death or injury. However, twice this volume of CCl4 caused total cell death, Enzyme immunoassay (EIA) failed to detect prostaglandin E(2) (PGE(2)) synthesis in hepatocyte cultures after the first day in culture, under a variety of cell culture conditions, Conventional hepatocyte cultures, but not ricin-purified hepatocytes, synthesized thromboxane B-2 (approximately 300 pg/mg protein) and prostaglandin D-2 (PGD(2)) (range, 1,000-6,000 pg/mg protein), Conventional hepatocyte cultures released prostaglandin F-2 alpha (PGF(2 alpha)) immunoreactivity (ranging from approximately 900 to 1,800 pg/mg protein), Ricin purified hepatocyte cultures made at least half as much PGF(2 alpha) immunoreactivity as did corresponding conventional hepatocytes, However, cyclooxygenase inhibitors did not inhibit the portion of PGF(2 alpha) immunoreactivity made by ricin-purified hepatocytes, PGF(2 alpha) immunoreactivity released by ricin-purified hepatocytes cochromatographed with PGF(2 alpha), and probably represents F-2-isoprostanes resulting from lipid peroxidation in hepatocytes. F-2-isoprostane release was detected by immunoassay, Conventional cultures of rat hepatocytes contain Kupffer and endothelial cells, which can synthesize significant amounts of cyclooxygenase products. Highlypurified hepatocytes do not produce cyclooxygenase products, even with a maximal stimulus to lipid peroxidation. CCl4 causes the release of F-2-isoprostanes hom hepatocytes with or without observable cell injury, as detected by Trypan blue exclusion or lactate dehydrogenase (LDH) release.