Signal transduction in myocardial hypertrophy

Area of Science:

• Cardiology
• Molecular Biology
• Cellular Physiology

Background:

• Cardiac hypertrophy is a response to mechanical stress.
• The role of intracellular signaling in cardiac adaptation requires further elucidation.

Purpose of the Study:

• To investigate the mechanism by which ventricular wall stretch induces cardiac muscle cell growth.
• To determine the role of cyclic AMP (cAMP) in transducing mechanical stretch into cellular growth.

Main Methods:

• Isolated perfused rat hearts subjected to increased aortic pressure to induce ventricular stretch.
• Measurement of protein synthesis and ribosome formation rates.
• Quantification of intracellular cyclic AMP (cAMP) levels.
• Assessment of methacholine's effect on stretch-induced signaling.

Main Results:

• Ventricular wall stretch significantly accelerated protein synthesis and ribosome formation.
• Increased aortic pressure led to elevated cAMP levels, correlating with enhanced protein synthesis.
• Glucagon, which increases cAMP, also stimulated protein synthesis.
• Methacholine inhibited the effects of stretch on protein synthesis, ribosome formation, and cAMP.

Conclusions:

• Ventricular wall stretch is transduced into increased cAMP levels.
• cAMP acts as a key intracellular messenger mediating accelerated ribosome formation and protein synthesis during cardiac hypertrophy.
• Cholinergic signaling can modulate the hypertrophic response to mechanical stress.