Effect of L-histidine in vivo on human platelet function and arachidonic acid metabolism.

The effect of the amino acid l-histidine on human platelet function and arachidonic acid metabolism was studied in 18 healthy subjects with increased spontaneous platelet aggregation. The participants received placebo or l-histidine 3g/day for 7 days. The intake of l-histidine reduced the degree of spontaneous platelet aggregation (p less than 0.05) and inhibited the generation of platelet TXB2 by 47% (p less than 0.001) whereas platelet PGE2 synthesis was not affected. The mean l-histidine plasma concentration increased from 83.1 +/- 2.4 to 108 +/- 8.1 mumol/l (p less than 0.01) during the study. L-histidine was found to be an effective inhibitor of spontaneous platelet aggregation and platelet TXB2 generation. The present data verify interactions of histidine with human platelet function, probably mediated by arachidonic acid metabolites.