Negative inotropic effect of the combination of theophylline and ouabain in rabbit right ventricle: relation to elevated baseline tension.
The effects of the combined administration of theophylline and ouabain were examined in isolated right ventricular strips from the rabbit heart. Separately, each drug produced positive inotropism. If ouabain was added 10 minutes after theophylline, a decrease in dF/dt was observed. The presence of theophylline augmented the increase in baseline tension induced by ouabain, although theophylline, by itself, did not augment baseline tension at the concentrations tested. There was a significant correlation between the decrease in dF/dt and the rise in baseline tension. Theophylline did not enhance the ability of ouabain to induce arrhythmia. The actions of caffeine, theobromine and digoxin were also examined and gave similar results.
D000818:Animals; D003864:Depression, Chemical; D006352:Heart Ventricles / Q000187:drug effects; D066298:In Vitro Techniques; D008297:Male; D009200:Myocardial Contraction / Q000187:drug effects*; D010042:Ouabain / Q000008:administration & dosage / Q000494:pharmacology*; D011817:Rabbits; D013806:Theophylline / Q000008:administration & dosage / Q000494:pharmacology*
D010042:Ouabain; D013806:Theophylline