Gene expression patterns of the four cardiac chambers in the Thoroughbred horse.
Authors: Edling Charlotte E, Arevalo-Turrubiarte Magdalena, Premont Antoine, Uribe Marcos Castellanos, Forbes Bronte, Kemp Victoria, Weir Joe, Marr Celia, Lewis Rebecca, Jeevaratnam Kamalan
Journal: Journal of equine veterinary science
Summary
Understanding the molecular basis of cardiac performance in racehorses requires detailed knowledge of how gene expression varies across the four heart chambers, yet this remains poorly characterised in the equine literature. Researchers analysed tissue samples from both atria and ventricles of clinically normal Thoroughbreds using microarray technology to map gene expression patterns, with particular attention to genes governing electrophysiology and contractility. The right atrium emerged as metabolically distinct, showing significantly reduced expression of energy metabolism genes compared to all other chambers, whilst the left atrium demonstrated elevated cardiac conduction gene expression and suppressed cardiac morphogenesis genes relative to the ventricles; notably, atrial chambers exhibited greater left-to-right differences than ventricular chambers. Ion channel genes showed clear chamber-specific patterns, with potassium channels (KCNE1 and KCNJ2, KCNJ3, KCNJ4) displaying atrial-ventricular specificity, and calcium-regulating genes concentrated in the atria. For equine practitioners, these findings establish a molecular baseline of normal cardiac function in healthy racehorses, potentially enabling future comparison with horses displaying performance-limiting arrhythmias or conduction abnormalities, whilst the chamber-specific ion channel expression patterns may help explain breed-specific predispositions to certain cardiac conditions.
Read the full abstract on PubMed
Practical Takeaways
- •Understanding chamber-specific gene expression patterns provides baseline data for identifying cardiac abnormalities in performance horses
- •The distinct ion channel expression profiles between atria and ventricles may explain different electrophysiological properties and conduction patterns in healthy racehorses
- •Metabolic differences between right and left atrium suggest tailored approaches to cardiac assessment and potential performance optimization in athletic horses
Key Findings
- •Right atrium showed significantly lower expression of genes related to energy metabolism compared to ventricles and left atrium
- •Left atrium demonstrated higher expression of cardiac conduction genes and lower expression of cardiac morphogenesis genes compared to ventricles
- •Potassium channels KCNE1 and KCNJ2,3,4 exhibited distinct atrial-ventricular specificity
- •Calcium regulation genes were more abundant in both atria compared to ventricles