L-ARGININE NITRIC OXIDE PATHWAY ACTIVATION IN PLATELETS OF MIGRAINE PATIENTS WITH AND WITHOUT AURA/

Nitric oxide (NO) in platelets has been proposed as a promising tool f or studying NO variations in migraine. In the present research the pla telet response to collagen and the basal and collagen-induced producti on of NO and cGMP in platelet cytosol were assessed in migraine patien ts (25 with aura and 35 without aura) both interictally and ictally, a nd compared with the same parameters in 30 age-matched control subject s. A reduced responsiveness to collagen was found in migraine patients , particularly those with aura, and this was more marked during attack s (ANOVA interictal periods: p<0.01, attacks: p<0.02) The basal and co llagen-stimulated production of NO and cGMP in the platelet cytosol wa s significantly higher in migraine patients with aura assessed in inte rictal periods than in control subjects, and this production was furth er increased during attacks (interictal period: NO ANOVA: p<0.001, ict al period: p<0.01; cGMP: interictal period p<0.01, ictal period: p<0.0 2). The increase in platelet NO and cGMP production was also evident, though to a lesser extent, in migraine patients without aura. The pres ent research supports the hypothesis of an activation of the L-arginin e/NO pathway in migraine patients, especially those with aura, and con firms the findings of a previous study of increased levels of L-argini ne in platelets of migraine patients studied in headache free-periods, and decreased collagen aggregation in whole blood.