Differences in thromboxane production between neonatal and adult platelets in response to arachidonic acid and epinephrine.
In this study, we have investigated the possible role of the pro-aggregatory arachidonic acid (AA) metabolite thromboxane, in the impaired function of neonatal platelets. In platelet-rich plasma thromboxane production (measured by radioimmunoassay of thromboxane B2) was not different between neonates and adults when stimulated by thrombin (at 0.1 or 1.0 U/ml) or collagen (70 micrograms/ml) although neonatal platelets produced decreased thromboxane (TBX2) 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 TXB2/10(6) platelets, respectively. Production of TXB2 in response to 0.1 U/ml thrombin was not dissimilar between neonates (1.01 +/- 0.46 pmol) and adults (1.04 +/- 0.38 pmol). When collagen was used as the aggregating agent, TXB2 production was also not significantly different with values of 2.44 +/- 0.48 and 1.90 +/- 0.46 pmol/10(6) platelets produced by adult and neonatal platelet-rich plasma, respectively. In response to 200 microM epinephrine, adult platelets produced 1.03 +/- 0.39 pmol TXB2/10(6) platelets while neonatal platelet TXB2 production was significantly decreased (0.15 +/- 0.04; P less than 0.05). Thromboxane production in response to AA, however, was markedly elevated in neonatal platelet-rich plasma. When 200 and 400 microM concentrations of AA were used as the aggregating stimuli, neonatal platelet rich plasma produced 3.17 +/- 0.77 and 8.0 +/- 1.47 pmol TXB2/10(6) platelets, respectively. These values were significantly elevated P less than 0.02 and less than 0.005) when compared to mean values of 0.41 +/- 0.10 and 3.32 +/- 0.15 pmol in adult platelet-rich plasma.(ABSTRACT TRUNCATED AT 250 WORDS)
D000328:Adult; D016718:Arachidonic Acid; D001095:Arachidonic Acids / Q000494:pharmacology*; D001792:Blood Platelets / Q000187:drug effects / Q000378:metabolism*; D003094:Collagen / Q000494:pharmacology; D004837:Epinephrine / Q000494:pharmacology*; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D010974:Platelet Aggregation; D011863:Radioimmunoassay; D013268:Stimulation, Chemical; D013917:Thrombin / Q000494:pharmacology; D013929:Thromboxane B2 / Q000096:biosynthesis*; D013931:Thromboxanes / Q000096:biosynthesis*
D001095:Arachidonic Acids; D013931:Thromboxanes; D016718:Arachidonic Acid; D013929:Thromboxane B2; D003094:Collagen; D013917:Thrombin; D004837:Epinephrine