1. Key Objectives: To determine the density and activation of esophageal mast cells in non-cardiac chest pain patients. We expect to find mast cell activation, as measured by mast cell count or degranluation, tryptase staining, and histamine release, will be greater in NCCP patients compared to controls, and the increased mast cell activation will correlate with the severity of NCCP. These results will expand our understanding of the pathogenesis of esophageal originated NCCP, and allow the development of new diagnostic and treatment options.