Effect of acetylglyceryl ether phosphocholine (platelet-activating factor) and thrombin on acylation of exogenous...

Exogenous lysophosphoglycerides such as 1-O-acyl-2-(lyso)-sn-glycero-3-phosphocholine (lysoPC), 1-O-acyl-2-(lyso)-sn-glycero-3-phosphoethanolamine (lysoPE) and 1-O-alkyl-2-(lyso)-sn-glycero-3-phosphocholine (lysoGEPC) radiolabelled on the 1-O-aryl moiety were found to be acylated to the corresponding phosphoglycerides by rabbit platelets at different initial rates and to different extents. LysoPC and lysoGEPC were found to be the best precursors for specifically labelling the corresponding phosphoglyceride pool. Interestingly, synthetic 1-O-hexadecyl-2-acetyl-sn-glycero-3-phosphocholine (AGEPC) and thrombin were able to increase the initial rate of acylation of all these lysophosphoglycerides up to 4-6-fold in a concentration-dependent manner. The finding that stimulation of the acylation rate of the various lysophosphoglycerides was relatively independent of the stimuli used supports the hypothesis that this activation could be a new phenomenon associated with the reversible shape change observed in platelets after stimulation with AGEPC or thrombin.