PAF formation by H2O2-stimulated perfused canine carotid arteries

Perfusion of noncytotoxic concentrations of hydrogen peroxide (H2O2) through canine carotid arteries potentiates neutrophil adhesion to vessel endothelium. Platelet-activating factor (PAF) receptor antagonists block neutrophil adhesion to vessels pretreated with low millimolar concentrations of H2O2. We have used a specific gas chromatographic-mass spectrometric (GC-MS) assay for PAF and applied this to studies of canine carotid arteries perfused with H2O2. Vessels perfused with 1 and 10 mM H2O2 for 20 min produced PAF in a dose-dependent manner, 331 +/- 67 pg/g tissue with 1 mM H2O2 and 1160 +/- 194 pg/g with 10 mM. Vessels that had been denuded of endothelium with a balloon catheter prior to H2O2 perfusion produced similar quantities of PAF in response to H2O2 (220 +/- 72 pg/g and 960 +/- 210 pg/g with 1 and 10 mM, respectively). Cultured canine jugular venous endothelial cells produced PAF in response to 10 mM H2O2 (809 +/- 117 pg/10(7) cells) but carotid arterial smooth muscle cells did not. These results suggest that vascular cells other than endothelial cells may produce PAF following H2O2 perfusion of canine carotid arteries.