INCREASED PLATELET SEROTONIN CONTENT AND HYPERSECRETION FROM DENSE AND ALPHA-GRANULES IN-VITRO IN TENSION-TYPE HEADACHE

We investigated platelet aggregation and secretion from dense and alph a-granules in vitro in 28 tension-type headache (TH) patients and 26 h ealthy controls. We also measured basal platelet serotonin levels. Pla telet aggregation was normal in TH, but the secretion of serotonin and platelet factor 4 (PF4) was significantly increased in response to 0. 5 and 2.0 mug/ml collagen and to 1.0 mumol/l PAF. The basal platelet s erotonin levels were also higher in patients than in controls. The mec hanisms of platelet hypersecretion remain to be determined, but the in creased secretion of serotonin is probably in part related to the incr eased basal levels. The increased platelet serotonin in TH patients ma y reflect an enhanced serotonin turnover.