title: Decrease in heart contractility produced by ouabain in fibers exposed to theophylline.
abstract: The influence of theophylline on the inotrophic action of ouabain was investigated in strips of mammalian cardiac muscle. It was found that ouabain (2 X 10(-6) M) when added to preparations previously exposed to theophylline (4 mM) reduced the peak tension by 56%, the rate of tension development (dF/dt)max by 44% and the rate of twitch relaxation (dR/dt) by 65%. The possible mechanisms involved on the negative inotropic action of ouabain are discussed.
mesh_terms: D000255:Adenosine Triphosphate / Q000502:physiology; D000818:Animals; D002118:Calcium / Q000378:metabolism; D004347:Drug Interactions; D006168:Guinea Pigs; D066298:In Vitro Techniques; D009200:Myocardial Contraction / Q000187:drug effects*; D010042:Ouabain / Q000494:pharmacology*; D013806:Theophylline / Q000037:antagonists & inhibitors*
chemical_list: D010042:Ouabain; D000255:Adenosine Triphosphate; D013806:Theophylline; D002118:Calcium