Hydrogen peroxide, an inhibitor of platelet function: Effect on adenine nucleotide metabolism, and the release reaction

Abstract

The in vitro effects of H₂O₂ on platelet adenine nucleotide metabolism and on the ADP-induced platelet release reaction were examined. All studies were performed on human platelet-rich plasma (PRP) preincubated with (³ H)-adenine. Within 3 min of incubation with PRP, H₂O₂ (100–500 μM) caused an irreversible reduction in the (³ H)-ATP level with a concomitant increase in (³ H)-IMP and (³ H)-inosine and hypoxanthine levels. The adenylate energy charge (AEC) initially decreased while the ATP level fell. The AEC, however, returned to levels slightly lower than the control during further incubation. No leakage of ATP and ADP to plasma was observed. The fall in the steady-state levels of (³ H)-ATP increased with increase of the H₂O₂ concentration (decrease of 8.7–40% at H₂O₂ concentrations from 5 to 600 μM). H₂O₂ pretreatment of PRP caused absence of ADP-induced biphasic aggregation, partial inhibition of the primary wave, and complete inhibition of release of platelet nonmetabolic ATP and ADP. Our in vitro findings support the view that part of the inhibitory effect of H₂O₂ may be related to the lowering of metabolic ATP levels in platelets.