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Differences in thromboxane production between neonatal and adult platelets in response to arachidonic acid and epinephrine


Pediatric Research 18(9): 823-826
Differences in thromboxane production between neonatal and adult platelets in response to arachidonic acid and epinephrine
The possible role of thromboxane in the impaired function of neonatal platelets was studied. In platelet-rich plasma thromboxane production (measured by radioimmunoassay of thromboxane B2 [TXB2]) was not different between neonates and adults when stimulated by thrombin (at 0.1 or 1.0 U/ml) or collagen (70 .mu.g/ml) although neonatal platelets produced decreased TXB2 postepinephrine stimulation. In response to 1 U/ml thrombin, adult and neonatal platelet-rich plasmas produced mean values of 3.41 .+-. 0.35 (SEM) and 3.11 .+-. 0.49 pmol of TXB2/106 platelets, respectively. Production of TXB2 in response to 0.1 U/ml thrombin was not dissimilar between neonates and adults. When collagen was used as the aggregating agnet, TXB2 production was also not significantly different. In response to 200 .mu.M epinephrine, adult platelets produced 1.03 .+-. 0.39 pmol TXB2/106 platelets while neonatal platelet TXB2 production was significantly decreased (0.15 .+-. 0.04). TXB2 production in response to AA, however, was markedly elevated in neonatal platelet-rich plasma. When 200 and 400 .mu.M concentrations of AA were used as the aggregating stimuli, neonatal platelet rich plasma produced 3.17 .+-. 0.77 and 8.0 .+-. 1.47 pmol TXB2/106 platelets, respectively. These values were significantly elevated when compared to mean values of 0.41 .+-. 0.10 and 3.32 .+-. 0.15 pmol in adult platelet-rich plasma. This elevated TXB2 production was not, however, inherent in neonatal platelets since when washed platelets were studied results were reversed. Adult platelets produced more TXB2 at all doses of AA evaluated. The elevated response to exogenous AA observed in neonatal platelet-rich plasma apparently results from as yet undetermined plasma factors. The reported deficiencies in platelet function in the newborn clearly do not result from deficient TXB2 production poststimulation with the physiologic aggregating agents collagen and thrombin.


Accession: 005151679

PMID: 6435080

DOI: 10.1203/00006450-198409000-00003



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