Background Bitter perception has a particularly important role in host defense.Beside the tongue,the gastro-intestinal tract also expresses various components of the bitter taste signaling pathway.However, to date, direct effects of bitter compounds on small intestinal motility have not been shown.This study investigated the effects of bitter compounds on the spontaneous contraction of longitudinal smooth muscle strips of rat ileum.Methods Isolated longitudinal smooth muscle strips of rat ileum were used for tension recording in vitro.Immunofluorescence staining was used to identify the localization of TAS2R10 receptors.