No abstract

The effect of H2O2 on platelet metabolism, aggregation and release was studied by the in vitro exposure of 3H-adenine labelled platelet rich plasma (PRP) to H2O2. On incubation of PRP with H2O2 (100 to 500 μM final cone.) over a 30 minute period, there was a mean drop of 38% in the baseline steady state levels of radioactive metabolic ATP, the fall occurring in the first 3 minutes of incubation, with a corresponding increase in the levels of radioactive inosinemonophosphate and hypoxanthine. This was not a nonspecific lytic effect on the platelet since no extracellular leakage of platelet nucleotides occurred during the incubation. Further, mean decreases of 8 to 38% in steady state levels of platelet metabolic ATP were observed during incubations of PRP with 5 to 500 μM H2O2 respectively. Finally, the action of H2O2 on adenosine diphosphate (ADP) induced biphasic aggregation and release was studied in PRP preincubated for 3 minutes with H2O2 (100 to 500 μM). Partial inhibition of the primary wave, and complete inhibition of the second wave of ADP induced aggregation was observed in the H2O2 pretreated platelets, con-commitant with inhibition of release of platelet non-metabolic ATP and ADP, when compared to the control saline preincubated platelets. Since H2O2 is generated in vivo by bacteria and leucocytes during phagocytosis, the in vivo effects of the described inhibition of H2O2 and its possible role in platelet-leucocyte-bacterial interaction requires further elucidation.