title: Factors affecting efficiency of cardiac contraction.
mesh_terms: D000818:Animals; D001001:Anura; D002118:Calcium / Q000494:pharmacology; D066298:In Vitro Techniques; D009119:Muscle Contraction; D010210:Papillary Muscles / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D005082:Physical Exertion; D011817:Rabbits; D051381:Rats
chemical_list: D002118:Calcium