QUALITATIVE MODELING OF MECHANOELECTRICAL FEEDBACK IN A VENTRICULAR CELL

Mechanical changes in the heart muscle can influence its electrical pr operties through a process called mechanoelectrical feedback (MEF). Th is feedback can operate via changes in calcium dynamics during the cro ss-bridge cycle or via mechanosensitive (stretch-activated) channels. We present a four-variable ordinary differential equation (ODE) system that caricatures the electrical and mechanical activity of a ventricu lar cell and their mutual interactions. A three-variable excitable sys tem with restitution properties of the FitzHugh-Nagumo type is coupled to a fourth equation which describes changes in cell length during a lightly loaded contraction. The resulting four-variable system models MEF in a cell and can be incorporated into spatially distributed model s for mechanoelectric behavior during wave propagation in the cardiac tissue. (C) 1997 Society for Mathematical Biology.