Effect of 13-hydroperoxy-9,11-octadecadienoic acid (13-HPODE) on arachidonic acid metabolism in rabbit platelets.

1. The effect of 13-hydroperoxy-9,11-octadecadienoic acid (13-HPODE) on the formation of thromboxane (TX) B2, 12-hydroxy-5,8,10-heptadecatrienoic acid (HHT) and 12-hydroxy-5,8,10,14-eicosatetraenoic acid (12-HETE) from exogenous arachidonic acid in washed rabbit platelets was examined. 2. 13-HPODE inhibited TXB2 and HHT formation without affecting 12-HETE production. 3. 13-Hydroxy-9,11-octadecadienoic acid which was produced rapidly from 13-HPODE, did not suppress the formation of TXB2 and HHT, indicating the requirement of the hydroperoxy moiety for the inhibitory effect of 13-HPODE on TXB2 and HHT formation. 4. Experiments utilizing mannitol and dimethyl sulfoxide (hydroxy radical scavengers) revealed that the action of 13-HPODE is not due to hydroxy radicals which are expected to be formed from 13-HPODE. 5. These results suggest that 13-HPODE is a selective inhibitor of platelet cyclo-oxygenase and may have functional effects within platelets.