Analogs and Antagonists of Platelet-Activating Factor

The metabolically stable analogue of PAF, carbamyl-PAF (cPAF), and the PAF receptor antagonists PCA-4248 (22 (link)), CV-3988 (23 (link)), and (±)trans-2,5-bis(3,4,5-trimethoxyphenyl)-1,3-dioxolane (hereafter referred to as dioxolane [24 ] were purchased from Biomol). Egg yolk phosphatidylcholine was purchased from Sigma-Aldrich. Dr. Peter Isakson (G.D. Searle & Co., St. Louis, MO) provided SC-236 the selective COX-2 inhibitor. Stock solutions of cPAF, PCA-4248, CV-3988, dioxolane, and SC-236 were prepared at 5 mM concentrations by dissolving each in a 50% DMSO/PBS buffer and diluted further in PBS before cell culture or injection into mice. A thin layer of phosphatidylcholine (5 mM in PBS) was spread into a polystyrene dish and irradiated with 200 J/m² UVB under an FS-40 sunlamp. Irradiated solutions of phosphatidylcholine are referred to as UV-PC. The spontaneously transformed mouse keratinocyte cell line PAM-212 was obtained from Dr. Stuart Yuspa (National Cancer Institute, Bethesda, MD).