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Preconditioning in isolated superfused rabbit papillary muscles
D M Walker1, M S Marber, J M Walker
1Division of Cardiology, Hatter Institute for Cardiovascular Studies, University College Hospital, London, United Kingdom.
The American Journal of Physiology
|April 1, 1994
Summary
This study demonstrates that isolated heart muscle can be preconditioned against damage, a process involving adenosine receptors and independent of blood flow. This finding opens avenues for studying human heart muscle preconditioning.
Area of Science:
- Cardiology
- Physiology
- Myocardial Research
Background:
- Myocardial preconditioning is typically studied in arterially perfused hearts.
- A model for preconditioning in isolated, superfused cardiac muscle is needed to study human tissues.
Purpose of the Study:
- To develop a model of preconditioning in isolated, superfused rabbit right ventricular papillary muscle.
- To investigate the role of adenosine receptors in this preconditioning model.
Main Methods:
- Isolated rabbit papillary muscles were superfused and field-stimulated.
- Preconditioning involved brief rapid pacing under substrate-free hypoxic conditions followed by reoxygenation.
- Subsequent prolonged hypoxia and reoxygenation were used to assess protection.
Main Results:
- Preconditioning significantly improved the recovery of developed force after hypoxia (50.6% vs. 27.4%).
- The protective effect was blocked by 8-(p-sulfophenyl)theophylline (SPT), an adenosine receptor antagonist.
- Pretreatment with (-)N6(2-phenylisopropyl)adenosine also conferred protection.
Conclusions:
- Isolated superfused papillary muscles can be effectively preconditioned.
- This preconditioning is independent of coronary flow and mediated by adenosine receptor activation.