Abstract
Activation of platelet(Plt)plasma membrane is associated to Cytochrome C(Cyt.C)reducing activity.We studied this activity in newborn Plts stimulated by low or high molar ADP, collagen,thrombin and opsonized-zymosan(opZ).Cord blood was collected from placental end of the cut umbelical cord.The platelet-rich plasmas(PRPs)were layered on Ficoll 23%(w/v) to eliminate leukocyte contamination.Zymosan was opsonized with adult citrated-plasma(AB Rh-).Cyt.C reduction was determined spectrophotometrically,and aggregation(in PRPs or Plt suspensions)by the change in light transmission.The Cyt C reduction was undetectable(n=20)in newborn Plts stimulated with all stimuli(adult controls:10-20 nmol/109 Plts/10 min)including collagen(4 μg/ml)and thrombin(1.67 U/ml)able to induce their aggregation.Newborn Plts did not aggregate after low molar concentrations of agonists(Hathaway,1970)or after immunologic stimulation(Del Principe,ESPHI 1985).opZ plus subthreshold ADP elicited a 90% aggregation, but not Cyt.C reduction.The defective membrane redox reactions reflect an alteration in the process leading to membrane activation,and possibly account for the impaired functional response of newborn platelets.
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Del Principe, D., De Santis, R., Pentassuglio, A. et al. DEFECTIVE REDUCING ACTIVITY OF NEWBORN PLATELETS. Pediatr Res 19, 1076 (1985). https://doi.org/10.1203/00006450-198510000-00050
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DOI: https://doi.org/10.1203/00006450-198510000-00050