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Decrease in heart contractility produced by ouabain in fibers exposed to theophylline
Research Communications in Chemical Pathology and Pharmacology
|June 1, 1980
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.
Insights
Theophylline significantly reduced ouabain's positive inotropic effects on cardiac muscle. Ouabain
Area of Science:
- Pharmacology
- Cardiovascular Physiology
Background:
- Ouabain is a cardiac glycoside known for its positive inotropic effects.
- Theophylline is a methylxanthine drug with complex cardiovascular actions.
Purpose of the Study:
- To investigate the influence of theophylline on the inotropic action of ouabain in mammalian cardiac muscle.
Main Methods:
- Experiments were conducted on isolated strips of mammalian cardiac muscle.
- Preparations were exposed to theophylline (4 mM) followed by ouabain (2 X 10(-6) M).
- Measurements included peak tension, rate of tension development (dF/dt)max, and rate of twitch relaxation (dR/dt).
Main Results:
- Theophylline pretreatment significantly attenuated ouabain's effects.
- Peak tension was reduced by 56%.
- The rate of tension development (dF/dt)max decreased by 44%, and the rate of twitch relaxation (dR/dt) by 65%.
Conclusions:
- Theophylline exhibits a negative inotropic effect when combined with ouabain.
- This suggests a complex interaction between theophylline and cardiac glycosides.
- Further research is needed to elucidate the precise mechanisms underlying this interaction.