PyrilamineHistamine H1 AntagonistsReceptors, Histamine H1HistamineHistamine AntagonistsReceptors, Histamine H2DiphenhydramineReceptors, HistamineHistamine AgonistsDimapritMethylhistaminesDoxepinImpromidineCimetidineHistamine H2 AntagonistsReceptors, Histamine H3Organic Cation Transport ProteinsGuinea PigsDose-Response Relationship, DrugMuscle, Smooth