Summary
The mechanism of the platelet release reaction, induced by collagen, is in certain respects different from that of ADP. Besides other facts, the PF 4 release and the availability of PF 3 and APh are not influenced by the concentrations of alpha or beta-receptor blocking agents which clearly interfere with the ADP-induced release.
The possible role of thrombosthenin (or its alpha-receptors in the participation of the release reaction is discussed.