Short communication: “Gene expression patterns of the four cardiac chambers in the Thoroughbred horse”.

The research focused on studying the patterns of gene expression in the four chambers of a Thoroughbred racehorse’s heart, with an emphasis on genes involved in the electrophysiology of the heart. The authors studied the left atrium, right atrium, left ventricle, and right ventricle under two categories: chamber-related differences and left-right related differences.

Method

• The team collected tissue samples from the left atrium (LA), right atrium (RA), left ventricle (LV), and right ventricle (RV) of the Thoroughbred racehorses.
• The total RNA was then analyzed using the microarray technique, which is a DNA-based method used to detect gene expression levels.

Chamber Related Findings

• Upon contrasting atrial against ventricular chambers, they found clear chamber related differences.
• The results indicated that the right atrium (RA) showed significantly lower expression of genes related to energy derivation and metabolism compared to both ventricles and left atria.
• The left atrium (LA), however, had higher expression of genes related to cardiac conduction and less expression of genes involved in cardiac morphogenesis compared to the ventricles.

Left-to-Right Related Findings

• When comparing the left side to the right side of the heart, the left-to-right related comparisons showed wider differences between the atria than between the ventricles.

Focus on Cardiac Ion Channels

• The research also mapped genes specifically involved in cardiac conduction and contractions.
• Some potassium channels, KCNE1 and KCNJ2,3 and 4, were found to have distinct atrial-ventricular specificity, meaning their expression varied between these chambers.
• On the other hand, genes involved in calcium regulation were more abundant in both atria compared to ventricles.

Conclusion

• This study provided a detailed overview of the gene expression pattern in a healthy racehorse.
• The findings may help further understand pathology of cardiac diseases and development of therapeutic methods in racing horses.