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(Circulation. 2008;117:1621.)
© 2008 American Heart Association, Inc.

Clinical Summaries

An extract of the first 250 words of the full text is provided, because this article has no abstract.

	Differential Behaviors of Atrial Versus Ventricular Fibroblasts: A Potential Role for Platelet-Derived Growth Factor in Atrial-Ventricular Remodeling Differences

 
Cardiac tissue fibrosis is important in the progression of heart disease and plays an important role in cardiac arrhythmogenesis, particularly for atrial fibrillation. In a variety of cardiac disease models, atrial fibrosis is much more prominent than fibrosis in the ventricles, even when the profibrotic stimulus appears to be operating comparably at both the atrial and ventricular levels. This study examined the hypothesis that differences between atrial and ventricular fibroblast properties contribute to the predominant atrial fibrotic phenotype. To assess this possibility, we compared morphological, secretory, and proliferative responses of canine atrial versus ventricular fibroblasts. Atrial fibroblasts showed in vitro and in vivo behaviors indicating a greater tendency to activated myofibroblast dedifferentiation. Atrial fibroblast proliferation responses were consistently greater than ventricular responses for a variety of growth factors, including fetal bovine serum, platelet-derived growth factor, basic fibroblast growth factor, angiotensin II, endothelin-1, and transforming growth factor-β₁. Atrial tissue showed larger myofibroblast density than ventricular tissue, particularly in the presence of congestive heart failure. Congestive heart failure atria had more active fibroblast division rates and enhanced gene expression of fibroblast-selective markers compared with ventricles. Gene microarrays revealed 225 differentially expressed transcript probe sets between paired atrial and ventricular fibroblast samples, including extracellular matrix, cell signaling, and metabolism genes, and identified platelet-derived growth factor as a potential contributor to atrial-ventricular fibroblast differences. Platelet-derived growth factor inhibition eliminated atrial-ventricular fibroblast proliferative response differences. Our results suggest that important differences exist in properties of atrial versus ventricular fibroblasts, that these differences contribute to . . . [Full Text of this Article]