An assessment of arachidonic acid metabolism in the platelet of the neonate was performed. The uptake of [14C]arachidonic acid into platelets of both the neonate and the adult were similar. Neonatal platelets, however, released a significantly greater amount (P less than .001) of prelabeled arachidonic acid (24.7% +/- 2.8%) in response to the physiologic agent thrombin when compared with platelets from adult control subjects (14.6% +/- 0.8%). When the activities of the lipoxygenase (12-L-hydroxy-5,8,10,14-eicosatetraenoic acid) and cyclooxygenase pathways (12-L-hydroxy-5,8,10-heptadecatrienoic acid and thromboxane B2) were evaluated following incubation of platelets with [14C]arachidonic acid, significant differences were observed between adult and neonatal platelets. Platelets from the neonate produced less (P less than .01) thromboxane B2 (11.1% +/- 1.7%) when compared with platelets from adult control subjects (19% +/- 1.7%). In contrast, the lipoxygenase product 12-L-hydroxy-5,8,10,14-eicostatetraenoic acid was increased (P less than .005) in the platelet from the neonate (41.5% +/- 2%), when compared with the adult (31.2% +/- 2.1%). The observation that the availability of substrate arachidonic acid is increased in the platelet of the neonate may have general implications in neonatal pathophysiologic processes.
