Stretch-induced upregulation of connective tissue growth factor in rabbit cardiomyocytes

Connective Tissue Growth Factor (CTGF, CCN2) is considered to play an important role in cardiac remodelling. We studied whether stretch is a primary stimulus to induce CTGF expression in vivo in rabbit heart, and in vitro in isolated cardiomyocytes and fibroblasts. Twenty weeks of combined volume and pressure overload resulted in eccentric left ventricular (LV) hypertrophy, with increased LV internal diameter (+36 %) and LV weight (+53 %). Myocardial CTGF mRNA and protein levels were substantially increased in the overloaded animals. In isolated adult rabbit cardiomyocytes, cyclic stretch strongly induced CTGF mRNA expression (2.9-fold at 48 h), whereas in cardiac fibroblasts CTGF-induction was transient and modest (1.4-fold after 4 h). Conditioned medium from stretched fibroblasts induced CTGF mRNA expression in non-stretched cardiomyocytes (2.3-fold at 48 h). Our findings indicate that stretch is an important primary trigger for CTGF-induction in the overloaded heart.