The relation of blood platelet survival and distribution to 14-C-serotonin distribution and excretion.

VALID REPRESENTATION of the lifespan and destruction of a specific cell type is provided by studies of labeled cells if a number of requirements are met. These include that the label should not be injurious to the cell, that there is no elution of the label, that there is no reutilization of label at time of cell death, that the age distribution of the labeled cell population should be known, and that there is no labeling of the precursors of the cell. The use of ‘4C-5-Hydroxytryptamine ( ‘4C-5-HT) as a blood platelet label probably does not meet all of these specifications.”2 However, ‘4C-5-HT infused bound to platelets is retained in the body to a far greater extent than when infused directly or when massive platelet destruction occurs in vivo, suggesting a unique role of platelets in determining the in vivo distribution and subsequent fate of 5-HT. In order to further explore this relationship, the in vivo distribution and the excretion of ‘4C-5-HT introduced as a platelet label was compared to the survival and distribution of platelets themselves measured independently by enumeration.