PT  - JOURNAL ARTICLE
AU  - Kell, Pamela J.
AU  - Creer, Michael H.
AU  - Crown, Kimberley N.
AU  - Wirsig, Karin
AU  - McHowat, Jane
TI  - Inhibition of Platelet-Activating Factor (PAF) Acetylhydrolase by Methyl Arachidonyl Fluorophosphonate Potentiates PAF Synthesis in Thrombin-Stimulated Human Coronary Artery Endothelial Cells
AID  - 10.1124/jpet.103.055392
DP  - 2003 Dec 01
TA  - Journal of Pharmacology and Experimental Therapeutics
PG  - 1163--1170
VI  - 307
IP  - 3
4099  - http://jpet.aspetjournals.org/content/307/3/1163.short
4100  - http://jpet.aspetjournals.org/content/307/3/1163.full
SO  - J Pharmacol Exp Ther2003 Dec 01; 307
AB  - We have previously demonstrated that thrombin stimulation of endothelial cells results in increased membrane-associated, Ca2+-independent phospholipase A2 (iPLA2) activity, accelerated hydrolysis of membrane plasmalogen phospholipids, and production of several biologically active phospholipid metabolites, including prostacyclin and platelet-activating factor (PAF) that is abolished by pretreatment with the iPLA2-selective inhibitor bromoenol lactone. This study was designed to further investigate the role of alternative PLA2 inhibitors, including methyl arachidonyl fluorophosphonate (MAFP, an inhibitor of cytosolic PLA2 isoforms), on phospholipid turnover and PAF production from thrombin-stimulated human coronary artery endothelial cells (HCAECs). Paradoxically, pretreatment of HCAEC with MAFP (5–25 μM) resulted in a significant increase in PAF production in both unstimulated and thrombin-stimulated cells that was found to be a direct result of inhibition of PAF acetylhydrolase (PAF-AH) activity. Pretreatment with MAFP did not significantly inhibit HCAEC PLA2 activity, possibly due to the localization of PLA2 activity in the membrane fraction rather than the cytosol. Bromoenol lactone did not inhibit PAF-AH activity, even at concentrations as high as 20 μM. We conclude that MAFP augments thrombin-stimulated PAF production by inhibition of PAF catabolism without affecting membrane-associated iPLA2 activity. The American Society for Pharmacology and Experimental Therapeutics