title: Discrimination of isotopes by living systems. I. Frog hearts in 39K and 41K.
mesh_terms: D000818:Animals; D001001:Anura; D006321:Heart / Q000187:drug effects*; D066298:In Vitro Techniques; D011188:Potassium / Q000494:pharmacology*; D011189:Potassium Chloride / Q000494:pharmacology; D011194:Potassium Isotopes
chemical_list: D011194:Potassium Isotopes; D011189:Potassium Chloride; D011188:Potassium