Effect of quinidine on the inotropic effect of digoxin in isolated cat or guinea-pig papillary muscle

  • Kathryn A. Taubert
  • C. Bufalino
  • T. Hair
  • C. Lafleur
Conference paper


The effect of quinidine pretreatment on the inotropic effect and tissue content of digoxin was studied in 18 cat and 13 guinea-pig isolated, isometrically contracting papillary muscles. Muscles were divided into pretreated and non-pretreated groups. Pretreated muscles received 10−5 M quinidine one hour before 2 × 10−6M digoxin was added. At the peak inotropic effect of digoxin, muscles in both pretreated and non-pretreated groups were assayed for digoxin content. Quinidine alone exerted a small but significant positive inotropic effect in cat papillary muscle, but did not alter guinea-pig muscle performance. Digoxin elicited a significant positive inotropic effect in all groups of muscles studied. In cat papillary muscle, however, both developed tension and the rate of tension rise (+dT/dt) were increased significantly less in the quinidine-pretreated muscles. There were no significant differences between pretreated and non-pretreated groups for the guinea-pig muscles. The non-pretreated cat papillary muscles had a muscle digoxin level of 1302 ng/gm wet weight, and this was reduced significantly to 657 ng/gm in the pretreated muscles. The non-pretreated guinea-pig muscles had a muscle digoxin level of 1599 ng/gm, and this was not significantly altered by quinidine pretreatment. These data suggest that an interaction between quinidine and digoxin exists in isolated cat papillary muscle, but this interaction is not apparent in guinea-pig muscle. Therefore, when studying the interaction between these two drugs, the choice of the animal species used may be important.


Papillary Muscle Positive Inotropic Effect Inotropic Response Develop Tension Tension Rise 
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Copyright information

© Springer-Verlag Berlin Heidelberg 1986

Authors and Affiliations

  • Kathryn A. Taubert
    • 3
  • C. Bufalino
    • 1
    • 2
  • T. Hair
    • 1
    • 2
  • C. Lafleur
    • 1
    • 2
  1. 1.Division of Biomedical SciencesUniversity of California at RiversideStocktonUSA
  2. 2.Departments of Physiology and Pharmacology, School of PharmacyUniversity of the PacificStocktonUSA
  3. 3.American Heart AssociationNational CenterDallasUSA

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