Regional Differences in Cardiac Marker Gene Expression and Branched-Chain Amino Acid Metabolism in the Bovine Heart

Although the hearts of large animals are known to exhibit regional heterogeneity in structure, function, and metabolism, their spatial patterns of gene expression remain poorly understood. Therefore, we investigated regional differences in gene expression across six anatomical regions of the bovine heart, including the atria, ventricles, interventricular septum, and apex (n = 3). The expression levels of genes related to cardiac development, structure, and branched-chain amino acid (BCAA) metabolism were analyzed using quantitative real-time PCR, and multivariate patterns were evaluated using principal component analysis (PCA). Histological analysis suggested no apparent structural differences among the examined regions. NKX2.5 expression showed no significant regional variation, suggesting conserved cardiomyocyte identity. Conversely, contractile genes (MYH7, MYL2, TNNI3, and TNNT2) and the BCAA metabolism-related gene BCKDHA were significantly more highly expressed in the ventricular myocardium than in the atrial regions. PCA clearly distinguished between the atrial and ventricular myocardium and indicated coordinated variations in contractile and metabolic gene expression. These findings of region-specific molecular heterogeneity in the bovine heart, characterized by regional differences in gene expression across the myocardium rather than morphological differences, provide new insights into the spatial regulation of cardiac function and highlight the value of the bovine heart as a model for studying myocardial specialization.