title: Papaverine-induced positive inotropism with failure to increase cyclic AMP in rat atria.
abstract: Phosphodiesterase inhibition by papaverine is likely to play a minor role in the rat atrial inotropic response because non-significant changes in cyclic AMP were obtained. Isoprenaline however raised the nucleotide levels three-fold and up to seventeen-fold when papaverine was added in a similar preparation. A prominent effect of papaverine was to lengthen relaxation instead of shortening it as did isoprenaline. The results suggest different sites of action, although overlapping effects cannot be excluded.
mesh_terms: D000818:Animals; D000242:Cyclic AMP / Q000378:metabolism*; D004558:Electric Stimulation; D005260:Female; D066298:In Vitro Techniques; D007545:Isoproterenol / Q000494:pharmacology; D009200:Myocardial Contraction / Q000187:drug effects*; D009206:Myocardium / Q000378:metabolism*; D010208:Papaverine / Q000494:pharmacology*; D051381:Rats; D013268:Stimulation, Chemical
chemical_list: D010208:Papaverine; D000242:Cyclic AMP; D007545:Isoproterenol