Kadsurenone distinguishes between different platelet activating factor receptor subtypes on macrophages and...

The effects of the antagonist kadsurenone on the platelet activating factor (Paf)-induced chemiluminescence of guinea-pig peritoneal macrophages and on pig peripheral blood leucocyte aggregation were compared. Linearity and slopes of unity of the Schild plots confirmed the competitive nature of the antagonism by kadsurenone. pA2 values indicated a 91 fold lower affinity of kadsurenone for leucocyte Paf receptors than for those in macrophages. It is concluded that these two types of Paf receptors are not identical and are provisionally designated Paf1 and Paf2 receptors, respectively.