[Cellular electric potentials in experimental cardiac hypertrophy]

Myocardial hypertrophy is considered as an adaptive mechanism of the heart submitted to mechanical overload manifested by an increase of ventricular mass. For the study of the myocardial hypertrophy different experimental models were proposed although the transposition of the results in clinical conditions is difficult. In the adaptive mechanisms of the heart of great importance are the electro-mechanical interrelations. Mechanical alterations during cardiac hypertrophy are characterized by a reduced shortening velocity and an increase of the time to peak tension. They are due to the prolongation of action potential duration especially of its plateau and a decreased rate of repolarization because of the increase of the peak ICa and ICa density, and the slower inactivations of the maximal ICa. Abnormalities of the K+ currents IK1 and IK may contribute to the prolongation of action potential duration. The instability of Ca2+ transients in hypertrophic myocardium can cause the apparition of cardiac arrhythmias.