UTP transactivates epidermal growth factor receptors and promotes cardiomyocyte hypertrophy despite inhibiting transcription of the hypertrophic marker gene, atrial natriuretic peptide.

In neonatal rat ventricular myocytes, activation of receptors that couple to the G(q) family of heterotrimeric G proteins causes hypertrophic growth, together with expression of "hypertrophic marker" genes, such as atrial natriuretic peptide (ANP) and myosin light chain 2 (MLC2). As reported previously for other G(q)-coupled receptors, stimulation of alpha(1)-adrenergic receptors with phenylephrine (50 microM) caused phosphorylation of epidermal growth factor (EGF) receptors as well as activation of ERK1/2, cellular growth, and ANP transcription. These responses depended on EGF receptor activation.