The Mechanism of the Hemostatic Function of Blood Platelets

Relationships between platelet function tests in normal and uraemic subjects

“…Platelet adhesiveness to glass appears to be mediated through the release of ADP from red cells during their passage through the glass bead column (Hellem, 1960 and1964;Gaarder, Jonsen, Laland, Hellem, and Owren, 1961), a step which is followed by aggregation between the platelets themselves (Wright, 1941;Salzman, 1963). A relationship might therefore be anticipated between the results obtained in tests of platelet adhesiveness and those found in tests of ADP-induced aggregation.…”

“…The relationship found in the present communication between platelet disaggregation and the Stypven time in normal controls may be explained in terms of the findings cited above. Aggregated platelets disaggregate because of degradation of ADP by plasma and platelet enzymes (Hellem and Owren, 1964;Salzman, Chambers, and Neri, 1966), and hence where disaggregation is early and substantial, rapid degradation of ADP may be expected to have occurred. Substances which accelerate ADP degradation also reduce platelet factor 3 availability (Hardisty and Hutton, 1966b;Horowitz and Papyoanou, 1968) and therefore both reduced platelet factor 3 availability and accelerated disaggregation might be expected in platelet-rich plasma with a high capacity to inhibit adenosine diphosphate.…”

Platelet aggregation and strenuous exercise

“…Platelet surface clotting systems have a key role in haemostasis and platelet function (Hellem & Owren, 1964). The final irreversible phase of platelet aggregation is thrombin-dependent.…”

The Nature of the Defects in Hemorrhagic Disorders

“…The aggregation of platelets by ADP is inhibited by AMP and ATP as shown by Born (13) and also by a number of other sub stances (14). The prolonged primary bleeding time in uremic patients is probably caused by defective aggregation (15).…”