Appearance of platelet-clumping substance in plasma of rabbits after intravenous injection of agar-solution, bacterial endotoxin or adrenaline.

I N 1958, Shimamoto et al.’ reported platelet aggregation induced by hepari iized plasma of rabbits treated with bacterial endotoxin, and concluded that this was due to an appearance of platelet-clumping substance in plasma. These results were confirmed in vitro by Des Prez, Horowitz and Hooks in 1961. Since then, many investigators have reported adenosine diphosphate (ADP), thrombin, adrenaline and several other substances which aggregated platelets in platelet-rich plasma. The present paper describes the appearance of a platelet-clumping substance in plasma, which may differ from ADP and others, after intravenous injection not only of bacterial endotoxin, but also of agar-solution or adrenaline.