Pharmacological properties of platelet strips

The pharmacological properties of human platelet strips were studied by recording changes in tension after the application of various compounds. The platelet strips were prepared by packing cold re-calcified human platelets over a sheer gelatinized nylon mesh. The contractile response of such a strip was dependent on the number of platelets sticking to the nylon mesh. The strip was contracted by the addition of platelet aggregation inducers such as ADP, norepinephrine, thrombin and collagen, thereby suggesting that the contractile response is mediated through membrane receptors on the platelets. The ED50 values of the aggregation agents which contracted the strip were much the same as those which induced platelet aggregation, thereby suggesting that contraction of the platelet strip is similar to platelet aggregation in platelet rich plasma (PRP). The addition of platelet aggregation inhibitors such as papaverine, W-7 and PGE1 relaxed the platelet strip. The ED50 values of the aggregation inhibitors which relaxed the platelet strip were also similar to those for platelet aggregation inhibition. The time course of the release of the preloaded [14C]serotonin from the platelet strips correlated well with that of the tension developed.