title: Differences in the potassium dependence of the myocardial action of some semisynthetic cardiotonic steroids.
abstract: Experiments on guinea pig isolated papillary muscle indicated different dependence of the functional actions of cardiac aglycones and some semisynthetic derivatives on the external K+, concentration. Whereas toxicity of the aglycones and their acetates was increased by low K+, that of the "alkylating" compounds remained unchanged; drug-induced contractility was increased uniformly. These differences are explained on the basis of the ATPase reaction scheme, including a carrier-mediated transport of cardiac glycosides.
mesh_terms: D000818:Animals; D002316:Cardiotonic Agents; D004073:Digitoxigenin / Q000031:analogs & derivatives / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D006168:Guinea Pigs; D009200:Myocardial Contraction / Q000187:drug effects; D009206:Myocardium; D011188:Potassium / Q000494:pharmacology*; D013327:Strophanthidin / Q000494:pharmacology
chemical_list: D002316:Cardiotonic Agents; D004073:Digitoxigenin; C025708:digitoxigenin-3-bromoacetate; D013327:Strophanthidin; D011188:Potassium