The effects of bicarbonate and acetate haemodialysis on platelet cyclic AMP concentration,thromboxane B2 release and aggregation

The effects of chronic uraemia and serial acetate (HDA) or bicarbonate (HDB) hacmodialysis on the aggregation, thromboxane B₂ (TXB₂) release and cyclic AMP (cAMP) concentration of platelets from arterial blood were studied in 14 uraemic patients (6 dialysed and 8 conservatively treated) and 10 controls. Platelets from uraemic patients, either dialysed or treated conservatively, exhibited a significantly higher cAMP level (P<0.005), a lower TXB₂ level (P<0.01), and a lower aggregability (P<0.001) than the controls. The platelet cAMP level was more markedly decreased after HDB than after HDA (P<0.05). Greater increases in platelet aggregation (P<0.05) and TXB₂ formation were observed after HDB than after HDA. The concentration of platelet cAMP and aggregability, and also the platelet cAMP and the TXB₂ level showed a significantly negative correlation (r=–0.7,P<0.05 andr=–0.60,P<0.05, respectively). There was a positive correlation between the platelet-derived TXB₂ and the aggregability (r=0.67,P<0.05). Although most patients had secondary hyperparathyroidism, the serum parathyroid hormone level did not correlate closely with the cAMP, TXB₂ or aggregation results. The dysfunction of uraemic platelets accompanied by a reduced TXB₂ release may be explained by an increased cAMP and a decreased arachidonic acid availability. HDB improves the platelet function to a greater degree than does HDA.