The relationship between 5-hydroxytryptamine and adenosine triphosphate in blood platelets.

In normal platelets a proportionality was found between the amount of adenosine triphosphate (ATP) and amount of 5-hydroxytryptamine (5-HT) in platelets both before and after incubating them in plasma to which 5-HT had been added. In patients receiving reserpine and in others with myeloid leukaemia, the amount of 5-HT in the platelets and the uptake of 5-HT by them were depressed, while the amount of ATP was normal. The possibility that ATP is involved in the accumulation of 5-HT by platelets is discussed.