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 V_max and K_m 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 V_max and K_m 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 μM and K_m but not in cluster headache and migraine patients. The 5-HT concentrations in whole blood correlated positively with V_max and K_m, respectively, in cluster headache and with K_m in healthy controls but not with V_max nor with K_m 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 V_max of MAO and low K_m 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 V_max and K_m of the 5-HT uptake into platelets.