Phenolic Metabolites Modulate Cardiomyocyte Beating in Response to Isoproterenol

Cardiovascular disease (CVD) is a public health concern, and the third cause of death worldwide. Several epidemiological studies and experimental approaches have demonstrated that consumption of polyphenol-enriched fruits and vegetables can promote cardioprotection. Thus, diet plays a key role in CVD development and/or prevention. Physiological β-adrenergic stimulation promotes beneficial inotropic effects by increasing heart rate, contractility and relaxation speed of cardiomyocytes. Nevertheless, chronic activation of β-adrenergic receptors can cause arrhythmias, oxidative stress and cell death. Herein the cardioprotective effect of human metabolites derived from polyphenols present in berries was assessed in cardiomyocytes, in response to chronic β-adrenergic stimulation, to disclose some of the underlying molecular mechanisms. Ventricular cardiomyocytes derived from neonate rats were treated with three human bioavailable phenolic metabolites found in circulating human plasma, following berries' ingestion (catechol-O-sulphate, pyrogallol-O-sulphate, and 1-methylpyrogallol-O-sulphate). The experimental conditions mimic the physiological concentrations and circulating time of these metabolites in the human plasma (2 h). Cardiomyocytes were then challenged with the β-adrenergic agonist isoproterenol (ISO) for 24 h. The presence of phenolic metabolites limited ISO-induced mitochondrial oxidative stress. Likewise, phenolic metabolites increased cell beating rate and synchronized cardiomyocyte beating population, following prolonged β-adrenergic receptor activation. Finally, phenolic metabolites also prevented ISO-increased activation of PKA-cAMP pathway, modulating Ca²⁺ signalling and rescuing cells from an arrhythmogenic Ca²⁺ transients' phenotype. Unexpected cardioprotective properties of the recently identified human-circulating berry-derived polyphenol metabolites were identified. These metabolites modulate cardiomyocyte beating and Ca²⁺ transients following β-adrenergic prolonged stimulation.