5-Hydroxytryptamine levels and platelet aggregation responses in subjects with acute migraine headache.

Blood 5-hydroxytryptamine levels were reduced during migraine attacks in patients who had not taken any drugs but the aggregation responses to 5-hydroxytryptamine of the blood platelets from these patients were similar to responses of platelets from migrainous subjects between attacks. This confirms earlier findings that a permanent difference exists in the behaviour of platelets from migrainous subjects. Blood 5-hydroxytryptamine levels were reduced during migraine attacks in patients who had taken ergotamine. The aggregation responses of platelets taken from migrainous patients on ergotamine both during and between attacks were inhibited, which is in agreement with results previously found for aggregation responses following the in vitro pre-incubation of control platelets with ergotamine. Blood 5-hydroxytryptamine levels were maintained during migraine attacks in patients who had taken analgesics and there was no reduction in the aggregation responses of their platelets.