Related Experiment Videos
Selective beta(1)-blockade improves cardiac bioenergetics and function and decreases neuroendocrine activation in
E Omerovic1, E Bollano, R Mobini
1Wallenberg and Lundberg Laboratories, Sahlgrenska University Hospital, 413 45, Göteborg, Sweden.
Abstract:
In spite of the solid evidence that beta-blockade reduces mortality and morbidity in congestive heart failure (CHF) this therapy continues to be underused in clinical praxis. The reason for this may lie in scarcity of knowledge about the mechanisms of beta-blockade action. The major aim of this study was to investigate in vivo whether selective beta(1)-blockade may improve cardiac energy metabolism in rats with myocardial infarction in early postinfarct remodeling phase. Myocardial infarction (MI) was induced in male Sprague-Dawley rats by ligation of the left coronary artery. Two different groups of rats were studied, rats with MI treated with metoprolol (5 mg/kg/h; n = 9) and rats with MI saline treated (n = 9). The treatment with metoprolol was given by subcutaneously implanted minipumps and was initiated at 3 days postinfarct and during the period of 4 weeks. All rats were investigated with noninvasive methods (31)P magnetic resonance spectroscopy (MRS) and transthoracic echocardiography 3 days after induction of MI and 4 weeks later. Phosphocreatine/ATP ratio was normalized after the treatment with metoprolol while it was 50% lower in the saline group (p < 0.001). In the metoprolol group stroke volume and ejection fraction increased while deceleration time of mitral early filling was longer (all p < 0.05). Left ventricular weight as well as volumes and dimensions were similar between the groups. Plasma levels of noradrenaline (p = 0.058), adrenaline (p < 0.01) and brain natriuretic peptide (p = 0.09) were lower in the metoprolol group. Selective beta(1)-blockade with high dose of metoprolol initiated in the early postinfarct phase improves myocardial energy metabolism and function and prevents overactivation of sympathetic system. The beneficial effect on myocardial bioenergetics may be an important mode of action of beta-blockers which contributes to the clinical benefits of the therapy in CHF.
Insights
Selective beta(1)-blockade with metoprolol improved cardiac energy metabolism and function in rats after myocardial infarction. This therapy may contribute to clinical benefits in congestive heart failure by enhancing myocardial bioenergetics.
Area of Science:
- Cardiology
- Pharmacology
- Biochemistry
Background:
- Beta-blockade is proven to reduce mortality in congestive heart failure (CHF), yet remains underused.
- Understanding the mechanisms of beta-blockade action is crucial for improving clinical practice.
- Early post-myocardial infarction (MI) remodeling is a critical phase for therapeutic intervention.
Purpose of the Study:
- To investigate the in vivo effects of selective beta(1)-blockade on cardiac energy metabolism in rats with early post-MI remodeling.
- To assess the impact of metoprolol on myocardial function and sympathetic system activation post-MI.
Main Methods:
- Myocardial infarction (MI) was induced in Sprague-Dawley rats.
- Rats received either metoprolol (5 mg/kg/h) or saline for 4 weeks, starting 3 days post-MI.
- Noninvasive (31)P magnetic resonance spectroscopy (MRS) and transthoracic echocardiography were used to assess cardiac function and energy metabolism.
Main Results:
- Metoprolol treatment normalized the phosphocreatine/ATP ratio, unlike the saline group.
- Ejection fraction and stroke volume increased in the metoprolol group.
- Plasma levels of noradrenaline, adrenaline, and brain natriuretic peptide were reduced with metoprolol treatment.
Conclusions:
- Selective beta(1)-blockade with metoprolol, initiated early post-MI, improves myocardial energy metabolism and cardiac function.
- This therapy helps prevent sympathetic system overactivation.
- Enhanced myocardial bioenergetics is a key mechanism contributing to the clinical benefits of beta-blockers in CHF.