Smooth muscle is responsible for the contractility of hollow organs, such as blood vessels, the gastrointestinal tract, the bladder, and the uterus. Its structure differs greatly from that of skeletal muscle. The human esophagus contains three layers of muscle in its walls, the outer longitudinal and inner circular layers of the main muscular coat and the muscular layer of the mucosa. Visceral smooth muscle cells makes up all three layers along the entire organ except for the most rostral few centimeters. Smooth muscle contraction is critical to peristalsis in the human esophagus and the contraction may be mediated by activation of phospholipase through two distinct mechanisms (increased intracellular Ca2 and G protein activation) and activating PKCepsilon-dependent mechanisms. In vitro study also shows that cultured human esophageal smooth muscle cells express voltage-dependent Na( ) channels.HESMC from AcceGen Biotech Research Laboratories are isolated from the human esophagus. HESMC are cryopreserved at secondary culture and delivered frozen. Each vial contains >5 x 10^5 cells in 1 ml volume. HESMC are characterized by immunofluorescent method with antibodies to Α-smooth muscle actin and desmin. HESMC are negative for HIV-1, HBV, HCV, mycoplasma, bacteria, yeast and fungi. HESMC are guaranteed to further expand for 15 population doublings at the condition provided by AcceGen Biotech Research Laboratories.