PDE5 inhibitors protect against post-infarction heart failure

Area of Science:

• Cardiovascular Science
• Mitochondrial Biology
• Pharmacology

Background:

• Heart failure (HF) is a major cause of cardiovascular morbidity and mortality.
• Post-infarction HF involves cardiac remodeling, dysfunction, and cardiomyocyte apoptosis.
• Mitochondrial dysfunction is implicated in the pathogenesis of heart failure.

Purpose of the Study:

• To investigate the effects of phosphodiesterase type 5 (PDE-5) inhibition with sildenafil on cardiac geometry, function, and apoptosis in a post-myocardial infarction heart failure model.
• To elucidate the role of the Sirt3/PGC-1alpha pathway in mediating the cardioprotective effects of sildenafil.

Main Methods:

• A rat model of post-infarction heart failure was established using left anterior descending coronary artery ligation.
• Sildenafil treatment was initiated 3 days post-ligation.
• Cardiac geometry and function were assessed.
• Cardiomyocyte apoptosis and mitochondrial function (ATP production, respiratory capacity, mitochondrial membrane potential [MMP], and ultrastructure) were evaluated.
• Sirt3 protein expression and PGC-1alpha acetylation levels were measured.
• Experiments were conducted in cultured neonatal mouse ventricular myocytes subjected to hypoxia.

Main Results:

• Sildenafil treatment attenuated left ventricular remodeling, cardiac dysfunction, and cardiomyocyte apoptosis in post-infarct HF rats.
• Sildenafil improved mitochondrial function, including ATP production, respiratory capacity, MMP, and ultrastructure.
• Sildenafil partially reversed the downregulation of Sirt3 protein and PGC-1alpha acetylation in peri-infarct regions.
• In hypoxic myocytes, sildenafil suppressed apoptosis, enhanced ATP production, and increased MMP, accompanied by increased Sirt3 and decreased PGC-1alpha acetylation.
• Knockdown of Sirt3 diminished the beneficial effects of sildenafil.

Conclusions:

• Sildenafil exerts significant cardioprotective effects against post-infarction heart failure.
• The beneficial actions of sildenafil are attributed to the improvement of mitochondrial ultrastructure and function.
• The Sirt3/PGC-1alpha pathway is a key mediator of sildenafil's cardioprotective effects.
• Sildenafil holds potential therapeutic value for energy-related cardiovascular diseases.