In vitro effects of PAF on venous endothelial cell actin disposition.

Venous endothelial cells have been stained in vitro for the contractile protein actin, using an immunofluorescence technique. Semi-automated image analysis showed that treatment with platelet-activating factor (PAF 5 x 10(-7) M) caused elongation of endothelial cells and alteration in their actin-staining characteristics. These changes are prevented by the PAF antagonist BN52021 (1 x 10(-5) M and 1 x 10(-6) M) and the absence of extracellular Ca++. It is suggested that it is the resultant decrease in intracellular Ca++ levels which is responsible for preventing the effects of PAF.