Carnosine and β-alanine metabolism enzymes and transporters are present in rat cardiomyocytes and human heart tissue
Background
The therapeutic potential of carnosine in mitigating cardiac stress, ischemia-reperfusion injury, and other forms of heart disease is promising, attributed to its antioxidant, anti-inflammatory, anti-glycation, and pH-buffering properties. Despite this, understanding the specific metabolism of carnosine and its precursor, β-alanine, within cardiac tissue has been a significant gap. Current standard-of-care often lacks targeted metabolic support for the heart's endogenous protective systems. Exploring how these compounds are metabolized in the heart is crucial for determining their viability and efficacy in future in vivo supplementation studies and developing novel therapeutic strategies for cardiac health.
Study Design
Two independent studies investigated carnosine and β-alanine metabolism. Study 1 treated differentiated H9c2 rat cardiomyocytes with 0.1-10.0 mM carnosine or β-alanine for 4, 24, and 72 hours. Gene expression was measured at 4 hours using real-time quantitative polymerase chain reaction (qPCR), and amino acid/histidine-containing dipeptide concentrations were analyzed at all time points via amino acid analyzer. Study 2 analyzed post-mortem human heart ventricle samples (n=16) for endogenous carnosine and β-alanine concentrations using HPLC-ESI+-MS/MS and metabolism-related protein expression using western blots.
Results
H9c2 cardiomyocytes expressed genes related to carnosine and β-alanine metabolism, with the notable exception of the β-alanine transaminase, AGXT2. Exogenously supplied carnosine and β-alanine were both effectively taken up and accumulated within these cardiomyocytes, demonstrating cellular permeability and retention. Carnosine supplementation did not significantly affect gene expression profiles. However, β-alanine supplementation specifically decreased the expression of the TAUT and PHT1 transporters, suggesting a regulatory feedback mechanism. Crucially, human heart ventricles were found to express carnosine- and β-alanine-related enzymes and transporters, confirming the presence of the necessary machinery for their metabolism in human cardiac tissue. Endogenous concentrations of both carnosine and β-alanine were also detected in human heart samples. > Cardiomyocytes and the human heart express the full complement of enzymes and transporters required to uptake β-alanine and synthesize carnosine, laying a foundation for future cardiac interventions.
Key Findings
- Rat H9c2 cardiomyocytes expressed most carnosine and β-alanine metabolism genes, except
AGXT2. - Exogenous carnosine and β-alanine were actively taken up and accumulated in H9c2 cells.
- β-alanine supplementation decreased
TAUTandPHT1transporter expression in H9c2 cells. - Carnosine and β-alanine metabolism enzymes and transporters are present in human heart ventricles.
- Endogenous carnosine and β-alanine were detected in human heart tissue.
Why It Matters
This foundational research significantly advances our understanding of cardiac carnosine and β-alanine metabolism, validating the heart's capacity to process these compounds. Understanding this metabolic pathway opens new avenues for targeted nutritional or pharmacological interventions to support cardiac health. It suggests that supplementing with carnosine or β-alanine could directly enhance the heart's endogenous protective systems. While not providing a direct human protocol, this study establishes the mechanistic basis, indicating that future in vivo studies and clinical trials investigating carnosine/β-alanine for conditions like ischemia-reperfusion injury or heart failure are biologically plausible. This knowledge is critical for developing precise dosing and timing strategies for cardiac-specific benefits.
carnosine
beta-alanine
cardiac health
metabolism
in vitro
human tissue