[Primary thrombocyte reactions in hemostasis and thrombogenesis and the possibilities of influencing them by drugs].

The primary haemostasis begins with the activation of the thrombocytes. This activation is induced by nucleotides, by the haemostasis-activating factor existing in most tissues, by thrombin, collagen, adrenaline, serotonin and other activators. The activation is accompanied by an increased inclination of the thrombocytes to adhesion and aggregation. Morphologically activated platelets show appendices and become ball-shaped. These processes are reversible in vivo and in vitro. Medicaments inhibiting the function of the platelets were above all selected on account of their effect inhibiting the aggregation and were clinically tested. It is uncertain in what respect inhibition of the aggregation and inhibition of the thrombosis correlate. A technique for the judgement of the inhibition of the tissue extract-induced change of the form of thrombocytes is demonstrated as a method for the measurement of the activation of the platelets. Acetylsalicylic acid influences the aggregation of platelets by inhibition of the cyclooxygenase in the thrombocytes. This leads to an inhibition of the thromboxane synthesis in the platelets which lasts for days, since it is irreversible. The spontaneous change of the form of the thrombocytes and the tissue extract-induced change of the form of the platelets by acetylsalicylic acid are, however, influenced only for the duration of 6-10 hours.