Summary
Per cent aggregation, release and content of adenine nucleotides, and specific radioactivity
were evaluated in citrated platelet-rich plasma (PRP) prepared from paired samples
of maternal and cord blood. Platelets of newborn infants aggregated normally in response
to high dose ADP (20 μM), strong collagen suspensions, and thrombin; however, when
compared with PRP from the mothers or from normal adults, per cent aggregation in
response to lower concentrations of ADP (2 μM), weak collagen, and part particularly
epinephrine was markedly reduced. Nucleotide release after stimulation of the newborns’
PRP with the latter two inducers was also impaired. ATP and ADP content of the newborns’
platelets was also significantly less than that of their mothers or of normal adults,
but specific activity was normal. The data suggest that the impairment of ADP release
in the platelets of newborn infants is due to decreased sensitivity to external stimuli.
Since metabolic ATP is necessary for the platelet release reaction, it is postulated
that the platelet dysfunction results from a lack of metabolic ATP.