Cardiac hypertrophy is triggered in response to mechanical stress and various neurohumoral factors, such as G-protein coupling receptor (GPCR) and gp130 cytokine receptor agonists. Recent studies have suggested cardiac Z-disc plays a pivotal role to regulate these cellular responses. Here, we demonstrate stimulations with GPCR agonists (norepinephrine, angiotensin II, and endothelin I) and phorbol ester activated and translocated protein kinase D1 (PKD1) to the Z-discs in neonatal rat cardiomyocytes in a protein kinase C (PKC)-dependent manner, whereas gp 130 agonist did not. Especially, upon the alpha-adrenergic receptor agonist stimulations, following the PKCepsilon-PKD1 complex formation, PKCepsilon-dependent activation of PKD1 was essential to induce hypertrophic responses. Constitutively active mutant of either PKD1 or PKCepsilon also induced cardiac hypertrophy ex vivo. Taken together, the PKCepsilon-PKD1 complex at Z-discs could play a pivotal role in the cardiac hypertrophy induced by GPCR agonists, at least ot-adrenergic receptor agonist. (C) 2004 Elsevier Inc. All rights reserved.