VIP and postural orthostatic tachycardia syndrome: The concept of agastrointestinal vasomotor disturbance accounting for symptomology in the RGIgroup dovetails well with some recent POTS investigations, emphasizingmesenteric hyperemia as a major finding in certain POTS subgroups [15].As postulated by Stewart et al. the mechanism of this hyperemia could include afocal denervation, or more likely, local neuroendocrine factors in the entericnervous system, such as nitric oxide or vasoactive intestinal peptide resultingin inappropriate vasodilation.