The effect of 1-year erythropoietin (rHu-EPO) treatment on the bleeding time, platelet aggregation, ATP and thromboxane B2 (TXB2) release, cyclic AMP (cAMP) concentration and platelet surface positive charge were studied in 8 haemodialysed children with chronic uraemia and 8 controls. The pre-dialysis haematocrit (Hct) was 0.21+0.01 before and 0.36+0.01 following 1 year of rHu-EPO therapy. At the end of this period the pre-dialysis bleeding time became normal (P<0.05); this was associated with a significant increase in platelet aggregability (P<0.05), ATP release (P<0.05) and TXB2 production (P<0.01), and with a significant decrease in platelet cAMP concentration (P<0.01). A further increase in platelet aggregation, ATP release and TXB2 production and a decrease in platelet cAMP concentration was observed following bicarbonate haemodialysis (BHD) (P<0.01). There was a significant positive correlation between platelet aggregation and ATP release (r=0.78, P<0.05), as well as platelet aggregation and TXB2 production (r=0.68, P<0.05). A significant negative correlation was found between platelet aggregability and cAMP concentration (r=-0.7, P<0.05). The platelet surface positive charge, which was significantly lower in the patients than in the controls (P<0.01), did not change during rHu-EPO therapy, nevertheless BHD resulted in a significant increase (P<0.05), suggesting the surface charge may influence platelet aggregation. In an in vitro and an in vivo study, rHu-EPO and the higher Hct did not increase platelet aggregation directly. Long-term administration of rHu-EPO stimulated complex functional and biochemical changes in the platelets of uraemic patients, which resulted in an improved aggregability.
ASJC Scopus subject areas
- Pediatrics, Perinatology, and Child Health