Comparison of CGRP and NO responses in the human peripheral microcirculation of migraine and control subjects

Calcitonin gene-related peptide (CGRP) and nitric oxide (NO) are two molecules shown to have a role in migraine pathophysiology. Our objective was to test the hypothesis that migraine subjects are particularly sensitive to these signal molecules. The cutaneous microvascular responses to endothelial and non-endothelial dependent dilators were tested using laser Doppler flowmetry in combination with iontophoresis. The blood flow responses to iontophoretic administration of the endothelium-dependent vasodilator acetylcholine (ACh), or to the endothelium-independent dilators sodium nitroprusside (SNP) and CGRP, and to local warming (44 degrees C) were compared in this controlled trial. The design was that of two arms: patients diagnosed with migraine without aura (n = 9) for > 10 years were compared with nine healthy subjects matched for age and gender (seven female and two male, age range 30-60 years). Iontophoretic administration resulted in local vasodilation. ACh induced a relaxation of 1225 +/- 245% (relative to baseline) in controls and 1468 +/- 368% (P > 0.05) in migraine. The responses to SNP were 873 +/- 193% in controls and 1080 +/- 102% (P > 0.05) in migraine subjects. The responses to CGRP were 565 +/- 89% in controls and 746 +/- 675% (P > 0.05) in migraine patients. The responses to local heating which induced maximum dilation did not differ between the groups (1976 +/- 314% for controls and 1432 +/- 226% in migraine; P > 0.05. We conclude that there is no change in the microvascular responsiveness of the subcutaneous microvasculature in migraine.