 The purpose of this study is to examine a new chemical entity with 5HT agonist activity and an inhibition of the nitric oxide synthase enzyme NOS in patients suffering from migraine with aura. Nitric oxide has diverse roles both in normal and pathological processes including the regulation of blood pressure, neurotransmission, and macrophage defense systems. NO is synthesized by three isoforms of the NOS enzyme: neuronal n, inducible i and endothelial e. Neuronal NOS nNOS is found mainly in neuronal tissue and regulates changes in response sensitivity and cellular plasticity; iNOS is found in macrophages and other tissue, produces NO in response to stress and injury and is one source of inflammation; eNOS is found in endothelial cells, responsible for vascular homeostasis and the presumed mechanism for the effects of nitroglycerine therapy in angina; nitroglycerine is an NO donor. NXN-188 is selectively inhibits nNOS. 