title: Effects of calcium on ouabain-induced inotropism in rat and guinea pig hearts.
abstract: In experiments on isolated rat and guinea pig hearts, the influence of different calcium concentrations (0.45-3.6 mM) on ouabain action was studied. A different time course of the inotropic action of ouabain in rat heart (t1/2 about 15 sec) and guinea pig cardiac muscle (t1/2 about 4 min) was found. Furthermore, compared to guinea pig hearts, a considerably enhanced "sensitivity" of the rat myocardium to ouabain at increased calcium concentrations could be established. These results are explained on the basis of a different mode of calcium in modulating the contractility within these two species.
mesh_terms: D000818:Animals; D002118:Calcium / Q000494:pharmacology*; D004071:Digitalis Glycosides / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D006168:Guinea Pigs; D007473:Ion Channels / Q000187:drug effects; D009200:Myocardial Contraction / Q000187:drug effects*; D010042:Ouabain / Q000494:pharmacology*; D051381:Rats
chemical_list: D004071:Digitalis Glycosides; D007473:Ion Channels; D010042:Ouabain; D002118:Calcium