Concentration and uptake of 5-hydroxytryptamine in platelets from cluster headache and migraine patients.

Concentrations of 5-hydroxytryptamine (5-HT) in platelets were determined in 33 cluster headache patients (17 males) and in 34 migraine patients (16 males) outside attacks. The 5-HT uptake into platelets was measured and the kinetic constants Vmax and Km determined in 26 cluster patients (14 males) and in 30 migraine patients (13 males). Significantly lower 5-HT concentrations in whole blood were found in cluster headache and migraine patients than in 50 healthy controls (19 males). The Vmax and Km values of the 5-HT uptake were significantly lower in cluster headache and migraine patients compared with 22 healthy controls (9 males). The 5-HT concentrations and the kinetics of the 5-HT uptake did not differ between cluster headache and migraine. In healthy controls a significant positive correlation was found between the 5-HT uptake rate at 0.25 microM and Km but not in cluster headache and migraine patients. The 5-HT concentrations in whole blood correlated positively with Vmax and Km, respectively, in cluster headache and with Km in healthy controls but not with Vmax nor with Km in migraine. There was no obvious relation between the kinetics of platelet monoamine oxidase (MAO) and the 5-HT uptake except for an increased incidence of low Vmax of MAO and low Km of the 5-HT uptake in cluster headache. The kinetics of the 5-HT uptake was apparently not related to the state of migraine. The results indicate a possible constitutional trait in cluster headache and migraine expressed as low 5-HT concentrations in whole blood and low Vmax and Km of the 5-HT uptake into platelets.