Smooth muscle is responsible for the contractility of hollow organs, such as blood vessels, the gastrointestinal tract, the bladder, and the uterus. The human stomach contains three layers of muscle in its walls, the outer longitudinal, the middle circular and the inner oblique. The visceral smooth muscle cells make up all three layers along the entire organ. Smooth muscle contraction is critical to peristalsis in the human esophagus and the contraction may be mediated by activation of phospholipase through increased intracellular Ca2+, G protein activation, and activation of PKCepsilon-dependent mechanisms. Studies in vitro have also shown that gastric smooth muscle cells express endothelin and endothelial nitric oxide synthase and calcium and sodium may act as current carriers in the generation of the plateau potential. HGSMC from ScienCell Research Laboratories are isolated from the human stomach. HGSMC are cryopreserved at passage one and delivered frozen. Each vial contains >5 x 105 cells in 1 ml volume. HGSMC are characterized by immunofluorescence with antibodies specific to α-smooth muscle actin. HGSMC are negative for HIV-1, HBV, HCV, mycoplasma, bacteria, yeast and fungi. HGSMC are guaranteed to further expand for 15 population doublings under the conditions provided by ScienCell Research Laboratories Recommended Medium It is recommended to use Smooth Muscle Cell Medium (SMCM, Cat. #1101) for culturing HGSMC in vitro.