Decrease in heart contractility produced by ouabain in fibers exposed to theophylline.
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.
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*
D010042:Ouabain; D000255:Adenosine Triphosphate; D013806:Theophylline; D002118:Calcium