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Muscarinic receptor modulation of basal and beta-adrenergic stimulated function of the failing human left ventricle

G E Newton1, A B Parker, J S Landzberg

  • 1Cardiovascular Division, Department of Medicine, Mount Sinai Hospital, the University of Toronto, Ontario, Canada.

The Journal of Clinical Investigation
|December 15, 1996
PubMed

Insights

Muscarinic receptor stimulation negatively impacts heart failure by slowing relaxation and reducing beta-adrenergic responses. This study reveals key insights into cardiac function modulation in heart failure patients.

Area of Science:

  • Cardiology
  • Pharmacology
  • Physiology

Background:

  • Heart failure is characterized by impaired left ventricular function.
  • Beta-adrenergic stimulation typically enhances contractility but can be less effective in heart failure.
  • The role of muscarinic receptors in modulating cardiac function during heart failure requires further elucidation.

Purpose of the Study:

  • To investigate the impact of muscarinic receptor modulation on left ventricular function.
  • To assess the interaction between muscarinic and beta-adrenergic pathways in normal and failing hearts.
  • To determine the specific effects of acetylcholine and atropine on cardiac contractility and relaxation.

Main Methods:

  • Intracoronary administration of acetylcholine and atropine in patients with heart failure and healthy controls.
  • Measurement of left ventricular +dP/dt (contractility) and isovolumic relaxation time (Tau).
  • Evaluation of responses to dobutamine (a beta-adrenergic agonist) alone and in combination with muscarinic agents.

Main Results:

  • Acetylcholine inhibited dobutamine-induced contractility in both normal and heart failure groups.
  • Acetylcholine prolonged isovolumic relaxation time (negative lusitropic effect) in heart failure patients.
  • Atropine partially reversed acetylcholine's effects, indicating muscarinic receptor involvement.

Conclusions:

  • Muscarinic receptor stimulation exerts an independent negative lusitropic effect on the failing human left ventricle.
  • Muscarinic stimulation antagonizes the beneficial effects of beta-adrenergic stimulation in heart failure.
  • Targeting muscarinic pathways may offer novel therapeutic strategies for heart failure management.

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