The uptake, storage, and efflux of serotonin in platelets from migraine patients

A recently developed method for analysing 5-hydroxytryptamine (5-HT) efflux from platelets preloaded with a small amount of 14C-5-HT enables the assessment of the relative size of the granular and the cytoplasmatic pools of 5-HT within the platelets and of the rate of spontaneous efflux from these two compartments. This method, together with conventional assessment of the 5-HT uptake measures Km and Vmax, was applied in this study, comparing platelets from 14 patients with common migraine and 10 patients with classic migraine with platelets from 25 healthy controls. All patients were unmedicated and in an attack-free period. Neither the total patient group nor either of the two subgroups differed significantly from the control group on any measure of 5-HT uptake or efflux. However, two differences approached the conventional significance level: the relative size of the granular compartment (Compartment III) was larger for classic than for common migraine, and the efflux rate from Compartment III was shorter for classic migraine than for the healthy controls (P approximately 0.10 in both cases). Further studies are required to show whether these differences are real and, if so, whether they have any relevance for the pathogenesis of migraine attacks.