P-nitrosodimethylaniline (P-NSDA), one of the OH radical (OH·) scavengers, inhibited platelet aggregation by ADP or arachidonic acid (AA), inducing a certain alteration in platelet phospholipid metabolism.
In the platelet aggregation, it has been reported that reactive oxygen species, OH·, is generated in the process of the concomitant AA metabolism, and modified the rate and extent of various reactions in it. Then, we studied the effects of OH· scavengers on platelet aggregation.
Washed rabbit platelets were incubated at 37°C for 4min with OH· scavengers (P-NSDA, thiourea, D-mannitol, urea and methional), lipoxygenase inhibitor (nordihydroguaiaretic acid; NDGA) or cyclooxygenase inhibitor (benzoic acid; BA) before aggregation was induced. P-NSDA inhibited ADP or AA-induced platelet aggregation about 70-80% in comparison with control, but other OH· scavengers had no effects on ADP, AA, thrombin or A23187-induced aggregation. On the other hand, BA and NDGA inhibited AA or ADP-induced aggregation and their inhibition patterns were similar to that of P-NSDA. So, we considered that the inhibition of P-NSDA on ADP or AA-induced aggregation was not induced by its effect of trapping OH· but by altering the phospholipid metabolism associated with the platelet aggregation.
To confirm these considerations, we tried to analyze phospholipid metabolites during AA-induced platelet aggregation treated with P-NSDA by TLC.
In the results, it was found that the pattern of TLC in the platelet treated with P-NSDA was greatly different from those treated with inhibitors of AA metabolism, such as aspirin and NDGA. These findings indicate that the inhibition of the platelet aggregation by P-NSDA relates with other phospholipid metabolism than AA metabolism in platelet associated with platelet aggregation and that P-NSDA may be useful for investigating phospholipid metabolism in platelet aggregation.