Chapman, R A Structure-activity relations for caffeine: a comparative study of the inotropic effects of the methylxanthines, imidazoles and related compounds on the frog's heart. [electronic resource] - The Journal of physiology Nov 1974 - 615-34 p. digital Publication Type: Journal Article ISSN: 0022-3751 Standard No.: 10.1113/jphysiol.1974.sp010726 doi Subjects--Topical Terms: Adenosine--pharmacologyAnimalsCaffeine--pharmacologyCyclic AMP--pharmacologyDose-Response Relationship, DrugHeart--drug effectsHeart Atria--drug effectsHistamine--pharmacologyHistidine--pharmacologyHydrogen-Ion ConcentrationHypoxanthines--pharmacologyImidazoles--pharmacologyIn Vitro TechniquesNaphazoline--pharmacologyPhentolamine--pharmacologyPilocarpine--pharmacologyPotassium--pharmacologyPyridines--pharmacologyRana pipiensSolutionsStructure-Activity RelationshipSurface TensionTheobromine--pharmacologyTheophylline--pharmacologyTolazoline--pharmacologyXanthines--pharmacology