[Effects of pentoxifylline and propentofylline on the turnover of polyphosphoinositides of the erythrocyte membrane and on the metabolism of arachidonic acid in platelets].

[gamma-32p] ATP incorporation into polyphosphoinositides of the erythrocyte membrane has been studied in the presence of increasing concentrations of pentoxifylline and propentofylline. Our results show an inhibitory effect on the labelling of phosphatidylinositol 4,5-bisphosphate and phosphatidylinositol 4-phosphate, higher with propentofylline. We have then demonstrated that these two drugs block the metabolism of arachidonic acid in platelets stimulated by thrombin. The inhibition is located at the first biochemical steps of platelet activation, probably on phospholipase C. These results are discussed in relation with the modifications of platelet cyclic AMP content.