Effects of 5-oxo-12-HETE and 8-trans-5-oxo-12-HETE on cytosolic calcium levels in human neutrophils. Neutrophils (3 × 10⁶ cells/mL) loaded with calcium green-1 were treated with either vehicle, 5-oxo-12-HETE (10 μmol/L; 8-cis) or 8-trans-5-oxo-12-HETE (10 μmol/L; 8-trans). Approximately 2 minutes later, 5-oxo-ETE (10 nmol/L) was added. Fluorescence was measured as described in Materials and Methods. The inset shows the inhibitory effects of different concentrations of 5-oxo-12-HETE (•) and 8-trans-5-oxo-12-HETE (○) on calcium mobilization induced by addition of 5-oxo-ETE (10 nmol/L). The values are means ± SE of determinations on platelets from three different donors.